Thread: Inverse functions.

I face another problem childish but still a problem

Find the inverse functions of

a) x ---> 2x+3
b)x---> 3x-4
c) x---> 2(x+5)
d) x----> 1 (x-1)

Originally Posted by MrGenuouse

I face another problem childish but still a problem

Find the inverse functions of

a) x ---> 2x+3
b)x---> 3x-4
c) x---> 2(x+5)
d) x----> 1 (x-1)

I'm going to show you how to get the inverse function with example a). The remaining examples have to be done similarly.

to #a):

From you'll get the equation of the function f:



To find the equation of the inverse function you have to swap the variables and solve this equation for y:





(Remark: You'll get the graph of by reflection of the graph of f at the line y = x)

... and now it's your turn!

Another way of thinking about it: f(x)= 2x+ 3 tells you "whatever x is, first multiply by 2, then add 3". To find the inverse of f, do the opposite of each step, in the [b]opposite order. The opposite of "multiply by 2" is "divide by 2" and the opposite of "add 3" is "subtract 3". So the inverse of f is "subtract three, then divide by 2": just as earboth got.