Question

For $f\left(x\right)=4x^7-18x^3+9$ evaluate $\underset{x\to -\infty }{lim}f\left(x\right)$

Answer 1

Given $f\left(x\right)=4x^7-18x^3+9$. So,

$\underset{x\to -\infty }{lim}f\left(x\right)\underset{x\to -\infty }{lim}{x}^7(4-18/x^4+9/x^7)=-\infty \left(4\right)=-\infty$