Question

determine of the function is one-one and find the inverse. f(x)=x-9

Answer 1

f(x) = x - 9 is the equation of a straight line. It is a one-to-one function because any horizontal line drawn will intersect the straight line at just one point. So it passes the horizontal line test make it a one-to-one function.

Find the inverse:
f(x) = x - 9
y = x - 9
solve for x. Add 9:
y + 9 = x
x = y + 9
Interchange x and y:
y = x + 9 is the inverse.