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21

Mark the correct alternative in the following:

If the function f(x) = cos|x| – 2ax + b increases along the entire number scale, then

Formula:- (i) 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)

Given:-

f(x) = cos|x| – 2ax + b

For increasing f’(x)>0

-sinx-2a>0

2a<-sinx