Question

Given the function f(x) = 5(x+4) − 6, solve for the inverse function when x = 19.

answer options are 1). 72 2).1 3). 84 4). 68

Answer 1

It's been a very long time since I done this, but if I can remember correctly you need to get x on one side and move the rest of the numbers to the other:

(really long method... you could shorten it if you wanted to):
f(x) = 5(x + 4) - 6
=> 19 = 5(x + 4) - 6
=> 19 = 5x + 20 - 6
=> 19 + 6 = 5x + 20
=> 25 = 5x + 20
=> 25 - 20 = 5x
=> 5 = 5x
=> 5/5 = x
=> 1 = x
Answer: 2) 1

Answer 2

Y = 5(x+4)-6
x = 5(y+4)-6
x = 5y +20 - 6
x= 5y +14
5y = x-14
y = (x-14)/5

when x = 19, y = (19-14)/5
y = 5/5
y=1

In short, Your Answer would be Option 2

Hope this helps!