posted by Veronica on .
How do I use the product rule to solve these two questions. Much appreciated! xo
Find the derivative for k(x) = (5x4 + 2)(3sin x)
Find the derivative for m(x) = -ex cos x at x = 1
First familarize yourself with the "product rule" for derivatives.
For a product of two functions, which I will call
f(x) = u(x) * v(x),
the derivative of the product function is
df/dx = u dv/dx + v du/dx
For your second question, let
u(x) = -e^x and v(x) = cos x
du/dx = -e^x and dv/dx = -sin x
df/dx = -e^x cos x + e^x sin x
Now you try the other one