integrate

**pnfuller** · December 11th 2012, 01:23 PM

if f is continuous and integrating from 0 to 4 f(x)dx =10 find what integrating from 0 to 2 f(2x)dx is

**Plato** · December 11th 2012, 02:08 PM

Originally Posted by pnfuller

if f is continuous and integrating from 0 to 4 f(x)dx =10 find what integrating from 0 to 2 f(2x)dx is

Let $u=2x~\&~du=2dx$ so $\begin{array}{*{20}c} x &\vline & 0 &\vline & 2 \\\hline u &\vline & 0 &\vline & 4 \\ \end{array}$ .

So $\int_0^2 {2f(2x)dx} = \int_0^4 {f(u)du}$

**pnfuller** · December 11th 2012, 02:13 PM

wouldn't it be 1/2f(2x) and do you have to do anything else to solve for what it equals like f(x)=10 in the first part, how do you find what f(2x) equals?

**Plato** · December 11th 2012, 03:29 PM

Originally Posted by pnfuller

wouldn't it be 1/2f(2x) and do you have to do anything else to solve for what it equals like f(x)=10 in the first part, how do you find what f(2x) equals?

Why don't you try this for yourself?

The is simple algebra, $\int_0^2 {2f(2x)dx} = \int_0^2 {f(2x)\left( {2dx} \right)}$ .

If $\int_a^b {f(t)dt} = C$ THEN $\int_{u(a)}^{u(b)} {f(u)du} = C$

Thread: integrate

LinkBack

Thread Tools

Display

integrate

Re: integrate

Re: integrate

Re: integrate

Similar Math Help Forum Discussions

Integrate sin^n(x)cos^m(x)

integrate

Integrate

Integrate

Integrate (sin(x))^2(cos(x))^2

Search Tags