Question 40: Let the function f(x) have the graph y=f'(x) as the figure below. The function \(y=f(\cos x)+x^{2}-x\) is covariate on the interval:

\(y^{\prime}=-\sin x_{1} f^{\prime}(\cos x)+2 x-1\)

Because the \(\cos x \in[-1 ; 1] \Rightarrow-\sin xf^{\prime}(\cos x) \in[-1 ; 1] \operatorname{which} 2 x-1 \geq 1 \Leftrightarrow x \geq 1\)

I guess \(y^{\prime}=-\sin x \cdot f^{\prime}(\cos x)+2 x-1 \geq 0, \forall x \geq 1\)

Or the above multivariable function \((1 ;+\infty)\)

Compare the answers choose A.

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