Q. 55.0( 1 Vote )

Mark the correct alternative in the following:

If the function f(x) = 2x2 – kx + 5 is increasing on [1, 2], then k lies in the interval.

A. (–∞, 4)

B. (4, ∞)

C. (–∞, 8)

D. (8, ∞)

Answer :

Formula:- The necessary and sufficient condition for differentiable function defined on (a,b) to be strictly increasing on (a,b) is that f’(x)>0 for all x(a,b)


f(x) = 2x2 – kx + 5



f(x)>0


4x-k>0


K<4x


For x=1


K<4

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