OpenStudy (anthonyn2121):

1 year ago
ganeshie8 (ganeshie8):

Hint : There is a very obvious substitution

1 year ago
OpenStudy (anthonyn2121):

I'm not the ebst at u substitutions but my teacher said that it would be easy if u=sqrt(x) and du=1/(2sqrt(x))

1 year ago
ganeshie8 (ganeshie8):

that works, but there is even a better substitution

1 year ago
OpenStudy (anonymous):

$\int\limits \frac{(1+3\sqrt{x})^4}{\sqrt{x}}dx$ Re writing some things makes it more easier to notice the substitution $2 \int\limits (1+3\sqrt{x})^4 .\frac{dx}{2\sqrt{x}}$

1 year ago
OpenStudy (anthonyn2121):

Can I substitute u=1+3sqrt(x)?

1 year ago
OpenStudy (anonymous):

yes!

1 year ago
OpenStudy (anonymous):

Infact one more step you could do $\frac{2}{3} \int\limits (1+3\sqrt{x})^4.\frac{3dx}{2\sqrt{x}}$

1 year ago
OpenStudy (anonymous):

Try the substitution you were talking about

1 year ago
OpenStudy (anthonyn2121):

I'm confused as to what I'm supposed to do with the $(3dx)/(2\sqrt{x})$ part.

1 year ago
OpenStudy (anthonyn2121):

I get that if I integrate u^4 I get (1/5)u^5 though

1 year ago
OpenStudy (anonymous):

$u=1+3\sqrt{x}$ Find the derivative with respect to x, you'll see why I did that shortly

1 year ago
OpenStudy (anthonyn2121):

Ok I get $\frac{ 3 }{ 2\sqrt{x} }$

1 year ago
OpenStudy (anonymous):

$\frac{du}{dx}=\frac{3}{2\sqrt{x}}$$du=\frac{3}{2\sqrt{x}}dx$|dw:1448776991550:dw|

1 year ago