Question

Given f(x) =2x+5 and g(x)= x^2 - 4, find each of the following. {please help i have a test on it tomorrow}

Answer 1

all we are doing is substitution and then a little math.

1.)  g(2t)  and 2.)  -4g(x) - 5f(x)

#1...g(x) = x^2-4    (let's factor this to be (x-2)(x+2) and then substitute 2t
   (x-2) (x+2) = (2t - 2) (2t + 2) use FOIL to solve
                         4t^2 + 4t - 4t - 4
                         (4t^2 - 4)

#2...-4g(x) - 5f(x)
     = -4(x^2 - 4) - 5(2x + 5)            use distributive property
       -4x^2 + 16 - 10x -25              combine like terms
       -4x^2 - 10x - 9                      solution