How do you find the end behavior of f(x)= -x^4+x^2f(x)=x4+x2?

1 Answer
Jul 8, 2015

f(x)->-\inftyf(x) as x->\pm \inftyx±

Explanation:

The function f(x)=-x^4+x^2f(x)=x4+x2 is a polynomial with a degree of 4 (the largest exponent), which is even. Also, the coefficient of the highest powered term is negative.

These facts are enough to conclude that f(x)->-\inftyf(x) as x->\pm \inftyx±. This means that the graph of ff goes down forever and ever without bound as |x||x| gets larger and larger without bound. To be a bit more precise, the graph of ff will go below and stay below any given horizontal line by choosing xx to be sufficiently far from zero.