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Question
Find the value of k. if 2x + y = 0 is one of the lines represented by 3x2 + kxy + 2y2 = 0
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Solution
Given, 2x + y = 0
⇒ 2x = –y ......(i)
Then, 3x2 + kxy + 2y2 = 0
⇒ 3x2 + kx(–2x) + 2(4x2) = 0 ......[From (i)]
⇒ 3x2 – 2kx2 + 8x2 = 0
⇒ 11x2 – 2kx2 = 0
⇒ k = `11/2`
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