Science:Math Exam Resources/Courses/MATH100/December 2010/Question 01 (c)/Solution 1

Using the Product Rule, we get:

$\displaystyle {\begin{aligned}f'(x)&=(x\cos {x})'\\&=(x)'(\cos {x})+x(\cos {x})'\\&=\cos {x}+x(-\sin {x})\\&=\cos {x}-x\sin {x}\end{aligned}}$