4
For which value[s] of p, will the lines represented by the following pair of linear equations be parallel
3x – y – 5 = 0
6x – 2y – p = 0
Two lines a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 will be parallel if
Here, in given equations,
∴ p ≠ 10
Therefore, p can take any real value other than 10.
Hence, option a is the correct answer.
Given pair of linear equations is
3x – y – 5 = 0 ......[i]
6x – 2y – p = 0 ......[ii]
On comparing with ax + by + c = 0 we get
We get,
a1 = 3, b1 = – 1, c1 = – 5
a2 = 6, b2 = – 2, c2 = – p
`a_1/a_2 = 3/6 = 1/2`
`b_1/b_2 = 1/2`
`c_1/c_2 = 5/p`
Since, the lines represented by these equations are parallel, then
`a_1/a_2 = b_1/b_2 ≠ c_1/c_2`
Taking last two parts, we get `1/2 ≠ 5/p`
So, p ≠ 10
Hence, the given pair of linear equations are parallel for all real values of p except 10.
Question 4 - CBSE Class 10 Sample Paper for 2020 Boards - Maths Standard - Solutions of Sample Papers for Class 10 Boards
Last updated at Nov. 1, 2019 by
For which value[s] of p, will the lines represented by the following pair of linear equations be parallel
3x − y − 5 = 0
6x −2y − p = 0
[a] all real values except 10 [b] 10 [c] 5/2 [d] 1/2
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Transcript
Question 4 For which value[s] of p, will the lines represented by the following pair of linear equations be parallel 3x − y − 5 = 0 6x − 2y − p = 0 [a] all real values except 10 [b] 10 [c] 5/2 [d] 1/2 Given lines 3x − y − 5 = 0 and 6x − 2y − p = 0 3x − y − 5 = 0 Comparing with a1x + b1y + c1 = 0 a1 = 3, b1 = –1, c1 = –5 6x − 2y − p = 0 Comparing with a2x + b2y + c2 = 0 a2 = 6, b2 = –2, c2 = –p Now, Since lines are parallel 𝑎_1/𝑎_2 = 𝑏_1/𝑏_2 ≠ 𝑐_1/𝑐_2 Comparing 𝑎_1/𝑎_2 = 𝑏_1/𝑏_2 ≠ 𝑐_1/𝑐_2 3/6=[−1]/[−2] ≠ [−5]/[−𝑝] 1/2=1/2 ≠ 5/𝑝 Therefore, 1/2 ≠ 5/𝑝 p ≠ 5 × 2 p ≠ 10 So, correct answer is [a] – all real values except 10
- Class 10
- Solutions of Sample Papers for Class 10 Boards
CBSE Class 10 Sample Paper for 2020 Boards - Maths Standard
Find the value[s] of p in the following pair of equations: 3x y 5 = 0 and 6x 2y p = 0, if the lines represented by these equations are parallel. Maths Q&A
Solution
Step 1: Compute the ratios of coefficients.
Given: pair of linear equations is
3x-y- 5=06x-2y-p=0
On comparing the given equations with ax+by+c=0 , we get
a1=3, b1=-1,c1=-5a2=6,b2=-2,c2=- p
a1a2=36b1b2=12c1c2 =5p
Step 2: Compute the required value.
Since the lines represented by these equations are parallel.
Then the condition is:
a1a2=b1b2≠c1 c2
On considering the last two parts, we get
12≠5p⇒p≠10.
Hence, the given pair of linear equations are parallel for all real values of p except 10.