For what value of K does the following system have an infinite number of solutions?
x + 2Ky - 8 = 0
2x - y - 16 = 0
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. -1/4
x + 2Ky - 8 = 0
⇒ x + 2Ky = 8 .....(1)
2x - y - 16 = 0
⇒ 2x - y = 16 .....(2)
If a1x + b1y = c1 and a2x + b2y = c2 then (a1/a2) = (b1/b2) = (c1/c2) [Infinite solutions]
Here, a1 = 1, b1 = 2K, c1 = 8 and a2 = 2, b2 = -1, c2 = 16
So, 1/2 = (2K)/(-1) = 8/16
Then, 1/2 = (2K)/(-1)
K = -1/4
Let's verify if this value of K satisfies the third ratio,
(2K)/(-1) = 8/16
(-1/2)/(-1) = 1/2
1/2 = 1/2
Therefore, the value of K for which the system has an infinite number of solutions is -1/4.