Posted by **Vicky** on Thursday, September 20, 2012 at 1:42am.

Use the table of integrals to find int cos^4 3x dx

I found the table: ∫cos^n u du = (1/n)cos^(n-1)u sinu + (n-1/n)∫sin^(n-2)u du = 1/4 cos^(4-1)u sinu + (4-1/4)∫sin^(4-2) u du

so what i did the problem: let u=3x then du=3dx

=1/4*1/3 cos^3u sinu + 3/4*1/3 ∫sin^2 u du.

=1/12 cos^3u sinu + 1/4 -cos^2 u +c..

so am i doing right step??

## Answer this Question

## Related Questions

- calculus II - ∫ tan^2 x sec^3 x dx If the power of the secant n is odd, ...
- Math integrals - What is the indefinite integral of ∫ [sin (π/x)]/ x^...
- Integration? - Sorry, i have a load of questions on integration... thanks for ...
- Calculus 2 Trigonometric Substitution - I'm working this problem: ∫ [1-tan...
- Calculus AP - hi again im really need help TextBook: James Stewart:Essential ...
- Calculus AP - Evaluate the integral interval from [0 to pi] t sin(3t)dt Use ...
- Integral Help - 1.) ∫ (sin x) / (cos^2 x) dx 2.) ∫ (1) / (1+x^2) dx ...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- mathematics - ∫▒dx/(x√(2x^2+5x+1)) 2. ∫▒dx/(x&#...