y=2x+3 is y in terms of x. The inverse is x in terms of y, so 2x=y-3 and x=½(y-3).
If y=f(x)=2x+3, then x=g(y)=½(y-3). The inverse function f-1(x)=g(x)=½(x-3). We can write this as y=½(x-3).
The red line is y=2x+3 and the blue line is y=½(x-3), the inverse function.
