I'm having a bit of trouble with this Maclaurin Series question. It should be simple enough but I can't get the answer which is given as x2. It's been a while since i've done series and my being rusty is a little annoying. Hopefully someone can help :) Consider:
Question asks to find the Quadratic Maclaurin Polynomial for f(x).
So this is what I did. First I got the nth derivatives:
f1(x) = x*cos(x) + sin(x)
f2(x) = -x*sin(x) + cos(x) + sin(x)
P2(x): 0 + x*0 + (x^2)(0 + 1 + 0)*(1/2!)
I'm sure i'm doing something blatantly wrong here but I can't seem to work it out. Fresh eyes might be useful :)
Thanks a lot.