SOLUTION: If f(x) = 2x + 3 and g(x) = (x - 3)/2, what is the value of f[g(-5)]? If f(x) = 5x - 7, what is f -1(x)?

Algebra ->  Rational-functions -> SOLUTION: If f(x) = 2x + 3 and g(x) = (x - 3)/2, what is the value of f[g(-5)]? If f(x) = 5x - 7, what is f -1(x)?       Log On


   

Question 116815: If f(x) = 2x + 3 and g(x) = (x - 3)/2, what is the value of f[g(-5)]?
If f(x) = 5x - 7, what is f -1(x)?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
If f(x) = 5x - 7, what is f -1(x)?
g%28x%29=%28x-3%29%2F2
g%28-5%29=%28-5-3%29%2F2
g%28-5%29=-4
f%28x%29=2x%2B3
f%28g%28-5%29%29=f%28-4%29=2%28-4%29%2B3
f%28g%28-5%29%29=-5
To find the inverse, we have to find a function g such that,
f%28g%28x%29%29=x
f%28g%28x%29%29=5g-7=x
5g-7=x
5g=x%2B7
g=%28x%2B7%29%2F5
f%5E-1%28x%29=g%28x%29=%28x%2B7%29%2F5