Answer:
-21.
Step-by-step 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
[tex]x^{2} +8x-9[/tex]
to
[tex](-6)^{2} +8(-6)-9[/tex]
Because a negative multiplied by another negative or itself cancels the negatives out, [tex](-6)^{2}[/tex] and [tex]6^{2}[/tex] are the same when evaluated**.
[tex]36+8(-6)-9[/tex]
Positive times negative makes negative, so [tex]8(-6)[/tex] is [tex]-48[/tex], which leaves
[tex]36-48-9[/tex]
Then by simplifying, you get
[tex]-12-9[/tex]
and finally
[tex]-21[/tex]
Hope this helped!
**Be careful though, because [tex](-6)^{2}[/tex] and [tex]-6^{2}[/tex] are not the same thing. [tex]-6^{2}[/tex] is read as [tex]-(6)^{2}[/tex], which implies that you're squaring 6, but the ending value is negative.
