Question

For the function f(x) = x² + x, what is the value of f(-5)?

Answer 1

f(-5) = -30

Explanation:

Re-arrange

`f(x) = x^2 + x\\f(-5) = -5^2+\left(-5\right)`

Exponents

`5^2=5* 5=25`

Now we have,

`=-25+\left(-5\right)`

"Add"

`-25+\left(-5\right)=-25-5\:\mathrm{if\:(-a)\\eq 0}\\=-25-5\\=-30`

Solution

`f(-5) = -30`

Hope this helps!