can someone help me with this question.

Question

I am not exactly sure what I am supposed to do for this question.  Can someone help me. i know how to do functions but this is completely new.

 

Let f (x) = 3x2 – 4x – 5 and g(x) = 2x + 1

(a) Find the composite function (f o g)(x) and simplify the results.


(b) Find (f o g)(-3) .

Answer 1

So, Lindsay, if I were to tell you to find f(3), you'd plug in 3 for every x.

 

3(3²) - 4(3) - 5 = 27 - 12 - 5 = 10.

 

With f(g(x)), we are going to plug g(x) in for every x.

 

3(2x + 1)² - 4(2x + 1) - 5

3(4x² + 4x + 1) - 8x - 4 - 5

12x² + 12x + 3 - 8x - 4 - 5

12x² + 4x - 6

 

Hope this helps!