1.

If 2 is a root of the equation x2 + bx + 12 = 0 and the equation x2 + bx + q = 0 has equal roots, then q is equal to(A) 8 (B) -8 (C) 16 (D) -16

Answer»

The correct option is: (C) 16

Explanation:

Since x = 2 is a root of the equation

x2 + bx + 12 = 0 

=> (2)2 + b(2) + 12 = 0

=> 2b = -16 => b = -8

Then, the equation x2 + bx + q becomes

x2 - 8x + q = 0                   ....(1)

Since (1 ) has equal roots => b2 - 4ac = 0

=> (-8)2 - 4(1)q = 0 => q =16



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