f(x)=5x^(2)+9x-5 where x=-9 find the function values

Question

I understand how to find function values for positives, but I dont really understand the negatives.

Answer 1

f(x) = 5x^2 + 9x - 5 where x = -9

It is the same just remember to account for the minus sign.  plug into the fundtion.

f(-9) = 5*(-9)^2 + 9 * (-9) - 5

f(-9) = 5*81 - 81 -5

f(-9) = 405 - 86

f(-9) = 319