`y = xcos(x) - sin(x)` Use the Product Rule or the Quotient Rule to find the derivative of the function.
You need to evaluate the derivative of the given function, using the product rule for the product x*cos x, such that:
`f'(x) = ((x)'(cos x) + (x)(cos x)') - (sin x)'`
`f'(x) = 1*cos x + x*(-sin x) - cos x`
Reducing like terms yields:
`f'(x) = - x*(sin x)`
Hence, evaluating the derivative of the function, using the product rule, yields `f'(x) = - x*(sin x).`