The integral is .

Consider .

Apply derivative on each side.

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Substitute and in . 

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Replace in above expression.

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Consider the anti derivative function as and integrand function as .

Take , then .

Graph :

Graph the integrand function and anti derivative function.

Observe the graph, 

When is negative, then is decreasing and is positive , then is increasing.

Hence the curve is derivative of the curve .

Therefore, is antiderivative of the integrand function .

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