Steps for Solving an Inequality Proof

[transgalactic]

the question and how i tried to solve it are in this link

http://img155.imageshack.us/img155/4710/55108660qi1.gif

 

[HallsofIvy]

You need a little bit more. It is true that
$$x- \frac{x^3}{3!}+ \frac{x^5}{5!}> x- \frac{x^3}{3!}$$
but you have to fit
$$sin(x)= \sum_{n=0}^{\infty}\frac{(-1)^nx^{2n+1}}{(2n+1)!}$$
into that. Notice that because this is an alternating series with decreasing terms, the entire "tail" (all terms past "n") is less than the difference between the n-1 and n terms.

 

[transgalactic]

what is the steps for the solution?

 

[mutton]

what is the steps for the solution?

https://www.physicsforums.com/showpost.php?p=2009603&postcount=2