Step-by-step explanation:
Given
f(x) = 2x + 9
f^-1 (x) = ?
Let
y = f(x)
y = 2x + 9
Interchanging the roles of x and y we get
x = 2y + 9
2y = x - 9
y = ( x - 9) / 2
Therefore
⏩f^-1(x) = (x-9)/2
Hope it will help :)