Finals revew of functions

May 2010
8
0
I have my math finals next week and i still don't understand how to even start to do functions. These aren't even 1/4 of the problems on my review sheet. These are just the ones I don't remember how to start(Worried) Can some one please help me through these?

Find g[h(x)] and h[g(x)]
"I was able to do all 10 questions but these 2"
g(x)=x+4
h(x)=x+9

g(x)=|x|
h(x)= x-3

if f(x) =x^2, g(x)=3x, and h(x) = x-1 find each of the following
"I don't remember learning about this in class"
g[f(x)]

[f o h](3)

Find the inverse of each function
f(x)=3x-4 "is the answer f(x^-1)=(x-6)/3"

g(x)= (-3x+1)/2

h(x) = 4x^2 +12x + 9

Are the following functions inverses
"I don't even know what to do here"
f(x) = (2x-8)/2

g(x) = x +4
 

pickslides

MHF Helper
Sep 2008
5,237
1,625
Melbourne
There are a lot of quesitons here, did you make some attempts? if so you should post them

Find g[h(x)] and h[g(x)]
"I was able to do all 10 questions but these 2"
g(x)=x+4
h(x)=x+9
\(\displaystyle g[h(x)] = (x+9)+4=\dots\)

\(\displaystyle h[g(x)] = (x+4)+9=\dots\)

if f(x) =x^2, g(x)=3x, and h(x) = x-1 find each of the following
"I don't remember learning about this in class"
g[f(x)]

[f o h](3)
\(\displaystyle g[f(x)] = 3(x^2)\)

\(\displaystyle [f \circ h](3) = (3-1)^2\)




Find the inverse of each function
f(x)=3x-4 "is the answer f(x^-1)=(x-6)/3"
Nope

\(\displaystyle x=3y-4\)

\(\displaystyle x+4=3y\)

\(\displaystyle \frac{x+4}{3}=y\)

\(\displaystyle f^{-1}x=\frac{x+4}{3}\)

Are my answers correct?