Number of points in (-∞, ∞) , for which x^2-x sin x-cos x=0 , is

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Trigonometrical Equations

medium

The number of points in $(-\infty, \infty)$, for which $x^2-x \sin x-\cos x=0$, is

A

$6$

B

$4$

C

$2$

D

$0$

(IIT-2013)

Solution

$x^2=x \sin x+\cos x $

$f(x)=x^2 $

$g(x)=x \sin x+\cos x $

$g^{\prime}(x)=\sin x+x \cos x-\sin x $

$g^{\prime}(x)=x \cos x$

Standard 11

Mathematics

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