Find the inverse of the function g(x)=(4+3x)/(5-x)

For simplicity first rewrite as y=(4+3x)/(5-x). Now swap any x for a y, and any y for an x. This leaves the equation x=(4+3y)/(5-y). Our goal is to make y the subject of the formula. Multiply both sides by (5-y) to get rid of the denominator on the right hand side of the equation. At this stage we have x(5-y)=(4+3y). Subtract (4+3y) from both sides and expand the x(5-y) term. What we get is 5x-xy-4-3y=0. Collect all the y-terms together to get y(-3-x)+5x-4=0. Now move all the non-y-terms to the right hand side of the equation: y(-3-x)=4-5x Divide through by (-3-x) to obtain y=(4-5x)/(-3-x). Note this can be written as y=(5x+4)/(-1)(3+x). Then we rewrite this as y=-(5x+4)/(3+x) which is the inverse of the original function g(x)=(4+3x)/(5-x).

MM

Related Maths A Level answers

All answers ▸

State the interval for which sin x is a decreasing function for 0⁰ ≤ x ≤ 360⁰.


You're on a game show and have a choice of three boxes, in one box is £10, 000 in the other two are nothing. You pick one box, the host then opens one of the other boxes showing it's empty, should you stick or switch?


Use integration to find the exact value of [integral of] (9-cos^2(4x)) dx


What is a geometric series?