For the curve

MATHEMATICS · Multi-part · AP · Calculus AB · Differentiation: Definition and Fundamental Properties · Differentiation: Definition and Fundamental Properties

Problem

For the curve y=xcos⁡xy=x\cos x, consider the interval 0<x<2π0<x<2\pi. (i) Obtain dydx\dfrac{dy}{dx}. (ii) Determine all values of xx in the given interval for which the tangent to the curve is horizontal. (iii) For each value of xx found in part (ii), state whether the curve is rising or falling immediately to the right of that point, giving reasons based on the derivative.

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