If one root of the equation lx^2+mx+n=0 is - 92 (l, m and n are positive integers) and m 4n = lm, then l+n is equal to

JEE Main Mathematics question

If one root of the equation is (, and are positive integers) and , then is equal to

(A)
(B)Correct
(C)
(D)

Answer: (B)

Solution

gives , so the discriminant is and the roots are equal, each , hence . Then gives , and integers need to be a multiple of ; the smallest choice is , , . So , option (B). Note:

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Question ID VK-013473