Which expression represents the substitution u=5xu = 5xu=5x applied to the integral ∫cos(5x)dx\int \cos(5x) dx∫cos(5x)dx?
∫cos(u)du\int \cos(u) du∫cos(u)du
15∫cos(u)du\frac{1}{5} \int \cos(u) du51∫cos(u)du
5∫cos(u)du5 \int \cos(u) du5∫cos(u)du
∫15cos(u)du\int \frac{1}{5} \cos(u) du∫51cos(u)du