I am given y=f(x)=tan(2tan^{-1}x+\frac{\pi}{4}) for [ltex]-0.4<=x<=0.4[/tex] and asked to expand this using mclaurin's series which gives g(x)=1+4x+8x^2+20x^3+...
I was then asked to find the range of values of x for which the values of g(x) differs from f(x) by less than 0.5