Evaluate the expression

Question

(f o g)(9) when f(x)=-7x-9 and g(x)=9x^2+7x-6

Answer 1

(f o g)(9)=f(x), where x=g(9)=9*(9^2)+7*9-6=786.

 

Now Sand, I believe you messed up typing f(x) out, but you should still reach the answer on your own by solving for what f(786) is.

 

EDIT:

Thanks for providing the correct formulas so I can finish helping you.

f(786)=-7*786-9= -5511

 

I hope to answer more of your questions.

-cldp

Answer 2

f(x) = -7x - 9

g(x) = 9x² + 7x - 6

f o g(x) = -7(9x² + 7x - 6) - 9

f o g(x) = -63x² - 49x - 42 - 9

f o g(x) = -63x² - 49x - 51

f o g(9) = -63(9)² - 49(9) - 51

f o g(9) = -63(81) - 49(9) - 51

f o g(9) = -5103 - 441 - 51

f o g(9) = -5595