# If f(x) = 3x^2-x, what is f(-5)?

Jul 4, 2018

$80$

#### Explanation:

$f \left(- 5\right)$ means that $x = - 5$. With this in mind, we can plug this into $f \left(x\right)$. We will get

$f \left(- 5\right) = 3 {\left(- 5\right)}^{2} - \left(- 5\right)$

This simplifies to

$3 \left(25\right) + 5 = 80$

Hope this helps!

Jul 4, 2018

$80$

#### Explanation:

$\text{substitute " x = -5 " into } f \left(x\right)$

$f \left(\textcolor{red}{- 5}\right) = 3 {\left(\textcolor{red}{- 5}\right)}^{2} - \left(\textcolor{red}{- 5}\right)$

$\textcolor{w h i t e}{\times \times} = \left(3 \times 25\right) + 5$

$\textcolor{w h i t e}{\times \times} = 75 + 5 = 80$