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August 28th 2008, 11:07 AM
ally79

check an answer?

Determine the integral:

6(3x+5)^11 dx

I got 6 (3x+5/36)^12 +C

A yay or Nay would be great if someone doesn't mind
August 28th 2008, 11:16 AM
Moo

Quote:

Originally Posted by ally79

Determine the integral:

6(3x+5)^11 dx

I got 6 (3x+5/36)^12 +C

A yay or Nay would be great if someone doesn't mind

Erm.... does Ynay work ? :D

It's (6(3x+5)^12)/36 +C=((3x+5)^12)/6 +C, not what you've written :p
Try to figure it out. Putting parenthesis can sometimes help ! ^^
August 28th 2008, 11:20 AM
Marine

Hi!

You can proved it by yourself by differentiating it ;)

or try the linear substitution

all the best, marine
August 29th 2008, 04:21 AM
Prove It

Quote:

Originally Posted by ally79

Determine the integral:

6(3x+5)^11 dx

I got 6 (3x+5/36)^12 +C

A yay or Nay would be great if someone doesn't mind

$\int 6(3x+5)^{11} dx$

Let $u=3x+5$ and so $\frac{du}{dx}=3$

So $\int 6(3x+5)^{11} dx=2\int 3(3x+5)^{11} dx = 2\int u^{11} \frac{du}{dx} dx$
$= 2 \int u^{11}du = \frac{1}{6} u^{12} +C = \frac{1}{6}(3x+5)^{12}+C$

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