Inverse Functions
Inverse functions are really simple, but you have to follow a step-byy-step method.
If you are given an f(x) = 2x + 19
And you are told to find f-1(x) you can do it by this method:
STEP 1: write out your f(x) formula, replacing the f(x) with y
Therefore, y = 2x + 19
STEP 2: Swap all your x's and y's
Therefore, x = 2y + 19
STEP 3, Make y the subject
Therefore,
2y = x - 19
y = (x-19)/2
STEP 4, Replace the y, with f-1(x)
Therefore,
f-1(x) = (x-19)/2
They might give you a harder question involving quadratics...
Lets say
f(x) = 2x2+18
y = 2x2+18
x = 2y2+18
2y2 = x - 18
y2 = (x - 18) / 2
y = + or - SQUARE ROOT of (x - 18) / 2
Be careful with the inverse in the quadratics, because you have to make sure the inverse fits within the domain or range given of the function