# How do you use substitution to find #x=-2# for #f(x) = -x^4+8x^3+13x-4#?

##### 1 Answer

May 8, 2018

#### Explanation:

#"substitute x = - 2 into "f(x)" and evaluate"#

#f(color(red)(-2))=-(color(red)(-2))^4+8(color(red)(-2))^3+13(color(red)(-2))-4#

#color(white)(xxxx)=-16-64-26-4=-110#