For part b I substituted the 22 into the inverse of the firs

For part b I substituted the 22 into the inverse of the first equation which is f^-1(x) = (x-9)/5 and got 6.2. When I entered it I got it wrong. I tried and used the first equation but instead of substituting it in the inverse, I set it equal to 5x-9, and solved for x and got 2.6 and it is still wrong. I am clueless to what to do next.

Let f(z) = 5z-9 , a. Evaluate f a. Evaluate f (11) 4 1 (11) Preview b. Determine the value of y so that f (y) = 22 * Preview c. Determine the value of b so that f 1(f(b)) 5 . Preview d. Evaluate f(f 1(129) Preview

Solution

b) f^-1(y) = (y+9)/ 5

22 = (y + 9) / 5

110 - 9 = y

y = 101

c) f^ - 1 ( f(b)) = 5

f(b) = 5b - 9

f(b) + 9 = 5b

b = [f(b) + 9 ] / 5

f^ - 1 ( f(b)) = 5

5 = ( b + 9 )/5

b +9 = 25

b = 25 - 9

b = 16

d) f ( f^-1 (129) = ?

f^ -1 (129 ) = 129 + 9 /5 = 138/5

f (138 / 5) = 5 * 138 / 5 - 9 = 138 - 9 = 129