## anonymous 3 years ago how do you find the sum of the series sigma n=0 ; 4 (cosn*pi) (3/4)^n

• This Question is Open
1. anonymous

use the equation maker

2. anonymous

$\sum_{n=0}^{\infty} 4 (\cos n \pi) (\frac{ 3 }{ 4 })^{n}$

3. anonymous

are you sure it is till infinity?

4. anonymous

yes

5. TuringTest

Perhaps you can use some trig identities in conjunction with the ratio test.