How do you differentiate y=e^(-5x)cos3x?

1 Answer
Apr 19, 2017

Use the Product Rule

Explanation:

The product rule is:

(d(gh))/dx = g'(h) + g(h')

Let g = e^(-5x) and h = cos(3x), then:

g' = -5e^(-5x) and h' = -3sin(3x)

Substituting into the product rule:

(d(e^(-5x)cos(3x)))/dx = -5e^(-5x)cos(3x) -3e^(-5x)sin(3x)

(d(e^(-5x)cos(3x)))/dx = -e^(-5x)(5cos(3x) +3sin(3x))