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Hai phương trình được gọi là tương đương khi
Phương trình nào sau đây tương đương với phương trình \[{x^2} - 4 = 0\]?
Khẳng định nào sau đây là đúng?
Chọn cặp phương trình không tương đương trong các cặp phương trình sau:
Khẳng định nào sau đây là sai?
Tập nghiệm của phương trình $\sqrt {{x^2} - 2x} = \sqrt {2x - {x^2}} $ là:
Phương trình \[x + \sqrt {x - 1} = \sqrt {1 - x} \] có bao nhiêu nghiệm?
Phương trình $\sqrt { - {x^2} + 6x - 9} + {x^3} = 27$ có bao nhiêu nghiệm?
Hai phương trình được gọi là tương đương khi
Phương trình nào sau đây tương đương với phương trình \[{x^2} - 4 = 0\]?
Khẳng định nào sau đây là đúng?
Chọn cặp phương trình không tương đương trong các cặp phương trình sau:
Khẳng định nào sau đây là sai?
Tập nghiệm của phương trình $\sqrt {{x^2} - 2x} = \sqrt {2x - {x^2}} $ là:
Phương trình \[x + \sqrt {x - 1} = \sqrt {1 - x} \] có bao nhiêu nghiệm?
Phương trình $\sqrt { - {x^2} + 6x - 9} + {x^3} = 27$ có bao nhiêu nghiệm?
Trong các phương trình dưới đây, phương trình nào tương đương với phương trình \[{x^2} = 4?\]
A.
B.
C.
\[{x^2} + \sqrt x = \sqrt x + 4\]
D.
Cho phương trình \[\left[ {{x^2} + 9} \right]\left[ {x - 9} \right]\left[ {x + 9} \right] = 0\]. Phương trình nào sau đây tương đương với phương phương trình đã cho?
A.
B.
C.
\[\left[ {x - 9} \right]\left[ {x + 9} \right] = 0\]
D.
Trong các phương trình sau, phương trình nào tương đương với phương trình x2=9
A.x2−3x+4=0.
B.x2−3x−4=0.
C.x=3.
D.x2+x=9+x.
Đáp án và lời giải
Đáp án:C
Lời giải:Lời giải
Chọn C
+x2=9⇔x=±3.
+x=3⇔x=±3.
Hai phương trình này có cùng tập nghiệm nên chúng tương đương.
Vậy đáp án đúng là C.
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Một số câu hỏi khác có thể bạn quan tâm.
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Read the following andmark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 37 to 43:
In early civilization, citizens were educated informally, usually within the family unit. Education meant simply learning to live. As civilization became more complex, however, education became more formal, structured, and comprehensive. Initial efforts of the ancient Chinese and Greek societies concentrated solely on the education of males. The post-Babylonian Jews and Plato were exceptions to this pattern. Plato was apparently the first significant advocate of the equality of the sexes. Women, in his ideal state, would have the same rights and duties and the same educational opportunities as men. This aspect of Platonic philosophy, however, had little or no effect on education for many centuries, and the concept of a liberal education for men only, which had been espoused by Aristotle, prevailed.
In ancient Rome, the availability of an education was radually extended to women, but they were taught separately from men. The early Christians and medieval Europeans continued this trend, and single-sex schools for the privileged through classes prevailed through the Reformation period. Gradually, however, education for women, in a separate but equal basis to that provided for men, was becoming a clear responsibility of society. Martin Luther appealed for civil support of schools for all children. Al the Council of Trent in the 16th century, the Roman Catholic Church encouraged the establishment of free primary schools for children of all classes. The concept of universal primary education, regardless of sex, had been born, but it was still in the realm of the single-sex school.
In the late 19th and early 20th centuries, co-education became a more widely applied principle of educational philosophy. In Britain, Germany, and the Soviet Union the education of boys and girls in the same classes became an accepted practice. Since World War II, Japan and the Scandinavian countries have also adopted relatively universal co-educational systems. The greatest negative reaction to co-education has been felt in the teaching systems of the Latin countries, where the sexes have usually been separated at both primary and secondary levels, according to local conditions.
A number of studies have indicated that girls seem to perform better overall and in science in particular. In single-sex classes, during the adolescent years, pressure to conform to stereotypical female gender roles may disadvantage girls in traditionally male subjects, making them reluctant to volunteer for experimental work while taking part in lessons. In Britain, academic league tables point to high standards achieved in girls’ schools. Some educationalists, therefore, suggest segregation of the sexes as a good thing, particularly in certain areas, and a number of schools are experimenting with the idea.
Question 42:When the concept of universal primary education was introduced, education __________.
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Read the following andmark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 37 to 43:
In early civilization, citizens were educated informally, usually within the family unit. Education meant simply learning to live. As civilization became more complex, however, education became more formal, structured, and comprehensive. Initial efforts of the ancient Chinese and Greek societies concentrated solely on the education of males. The post-Babylonian Jews and Plato were exceptions to this pattern. Plato was apparently the first significant advocate of the equality of the sexes. Women, in his ideal state, would have the same rights and duties and the same educational opportunities as men. This aspect of Platonic philosophy, however, had little or no effect on education for many centuries, and the concept of a liberal education for men only, which had been espoused by Aristotle, prevailed.
In ancient Rome, the availability of an education was radually extended to women, but they were taught separately from men. The early Christians and medieval Europeans continued this trend, and single-sex schools for the privileged through classes prevailed through the Reformation period. Gradually, however, education for women, in a separate but equal basis to that provided for men, was becoming a clear responsibility of society. Martin Luther appealed for civil support of schools for all children. Al the Council of Trent in the 16th century, the Roman Catholic Church encouraged the establishment of free primary schools for children of all classes. The concept of universal primary education, regardless of sex, had been born, but it was still in the realm of the single-sex school.
In the late 19th and early 20th centuries, co-education became a more widely applied principle of educational philosophy. In Britain, Germany, and the Soviet Union the education of boys and girls in the same classes became an accepted practice. Since World War II, Japan and the Scandinavian countries have also adopted relatively universal co-educational systems. The greatest negative reaction to co-education has been felt in the teaching systems of the Latin countries, where the sexes have usually been separated at both primary and secondary levels, according to local conditions.
A number of studies have indicated that girls seem to perform better overall and in science in particular. In single-sex classes, during the adolescent years, pressure to conform to stereotypical female gender roles may disadvantage girls in traditionally male subjects, making them reluctant to volunteer for experimental work while taking part in lessons. In Britain, academic league tables point to high standards achieved in girls’ schools. Some educationalists, therefore, suggest segregation of the sexes as a good thing, particularly in certain areas, and a number of schools are experimenting with the idea.
Question 41:When education first reached women, they were __________.
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question: The word “reckless” in line 11 is closest in meaning to ______________.
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question: Which of the following was NOT mentioned in the passage as a source of information for The Sea Around Us?
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question: Why does the author of the passage mention the report of the President’s Science Advisory Committee [lines 14-15]?
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question: The word “flawed” in line 14 is closest in meaning to ______________.
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question 44: According to the passage, what did Carson primarily study at Johns Hopkins University?
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question 43: The passage mainly discusses Rachel Carson’s work______________.
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question: It can be inferred from the passage that in 1952, Carson’s book Under the Sea Wind ______________.
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:
Rachel Carson was born in 1907 in Springsdale, Pennsylvania. She studied biology at college and zoology at Johns Hopkins University, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.
Carson’s first book,Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality. Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.
In 1962, Carson publishedSilent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled,recklessuse of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings wereflawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.
Question: When she published her first book, Carson was closest to the age of _______