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Siddharth Kothari (374)

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Ok, see let f(x) = (2x-pie)3+2x-cosx.

Let g(x) be the inverse of f(x).

Hence, g ( f(x) ) = x

        => g'(f(x)) . f'(x) = 1                          

Now, we have to find g' ( f(x) ) at x = pie.

Hence, f(pie) = (pie)3 +2(pie) + 1                (1)

f'(x) = 3 (2x - pie)2 .2 + 2 + Sinx

f'(pie) = 6(pie)2 + 2                                          (2)

 

Putting the values of (1) and (2) in the eqn. g'(f(x)) . f'(x) = 1         ;

g' ( ..) = 1/ (6 (pie)2 + 2) = the value of d/dx(inverse f(x)) at x=pie

 


Note the not : Numbers in life can't be chased.
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