Question 4 - CBSE Class 10 Sample Paper for 2020 Boards - Maths Standard
Last updated at Nov. 1, 2019 by Teachoo

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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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

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