# How do you evaluate 2x^4 when x = -1?

If $x = - 1$ then:
$2 {x}^{4} = 2 \cdot \left({\left(- 1\right)}^{4}\right)$
$= 2 \cdot \left(- 1\right) \cdot \left(- 1\right) \cdot \left(- 1\right) \cdot \left(- 1\right) = 2$
Exponentiation has higher precedence than multiplication, so first raise $- 1$ to the fourth power, then multiply by $2$.