A few problems encountered in exam revision

Hi. Any help with these would be much appreciated.

1. By considering the infinite series (SUMMATION SIGN with infinity on top and n=0 on bottom) of x^n for x< 1 show that:

(SUMMATION SIGN with infinity on top and n=0 on bottom) (n^2)(x^n) = x(1-x^2)/(1-x)^4.

I know this is to do with differentiating the previous derivative (x/(1-x)^2), but i got in a mess with it.

2.Find the indefinate integral of x^2*e^(x^3)

This is integration by parts but the x^3 is confusing me as i don't know how to deal with it. Basically my question is; how do you integrate e^(x^3)?

3. Use your calculator to find the value of the following expression when x=0.01 to 3dp:

y(x) = (e^(2x) - 2(1 +2x)^(1/2) +1) / (cos (x/2) -1)

The previous part of the question asked me to obtain Maclaurin series and re-write the above expression which i did. However when i substituted x=0.01 the 2 answers from the series and the exact did not match. I maybe approaching this question incorrectly. What is the meothod for this

Again any help would be much appreciated.