Question

Evaluate the expression when x= -6.
x² + 8x-9

Answer 1

-21.

Explanation:

Evaluating an expression is very similar to solving an equation, just without an equal sign.

Start by plugging in the given x value into your expression

`x^(2) +8x-9`

to

`(-6)^(2) +8(-6)-9`

Because a negative multiplied by another negative or itself cancels the negatives out,
`(-6)^(2)` and
`6^(2)` are the same when evaluated**.

`36+8(-6)-9`

Positive times negative makes negative, so
`8(-6)` is
`-48`, which leaves

`36-48-9`

Then by simplifying, you get

`-12-9`

and finally

`-21`

Hope this helped!

**Be careful though, because
`(-6)^(2)` and
`-6^(2)` are not the same thing.
`-6^(2)` is read as
`-(6)^(2)`, which implies that you're squaring 6, but the ending value is negative.

Answer 2

-21 is the answer :)