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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