# Math Help - Calculator Graphing Window Comparison

1. ## Calculator Graphing Window Comparison

I have been asked to see for what range of $x$ values $p(x)=1+x+(x^2/2)+(x^3/6)+(x^4/24)+(x^5/120)$ provides a good approximation of $f(x)=e^x$, when I graph them with a window of $-10\leq x\leq 10$ and $0\leq y\leq 200$, the two lines look fairly close at the top, but I know that $p(5)=91.4167$ and $f(5)=148.4132$.
I know that the lower limit of my answer is 0, but I can't figure out quite to find the upper limit. When I use the graph, do I look at differences in y values for specific x values, or differences in x values for specific y values?

2. I'm not certain either approach is invalid but I'm too tired to think on it so use the differences between the y-values at arbitrary values of x, of which I am certain is valid.