Hi, I'd like to know how to go about solving the following types of questions: Find $\displaystyle \int_{0}^{3}f(3x)dx$ if $\displaystyle \int_{0}^{9}f(x)dx=5$ Thanks for your help.
Follow Math Help Forum on Facebook and Google+
Originally Posted by Stroodle Hi, I'd like to know how to go about solving the following types of questions: Find $\displaystyle \int_{0}^{3}f(3x)dx$ if $\displaystyle \int_{0}^{9}f(x)dx=5$ Thanks for your help. Make the u sub $\displaystyle u=3x \implies du=3dx$ and note that when $\displaystyle x=0 \iff u=0 \text{ and } x=3 \iff u=9$ are your new limits of integration.
View Tag Cloud