# How to find the inverse of a function?

• Oct 31st 2010, 06:26 AM
khamaar
How to find the inverse of a function?
i have got this question and am a little confused..can u plz solve...(plz provide all steps)...

i) I=130+ (0.25).(Y)

ii) Y=(4).(I) -500
• Oct 31st 2010, 06:38 AM
Unknown008
I(Y) = 130 + 0.25Y

Make Y the subject of formula and then, 'change' the variables, that is replace I by Y and Y by $I^{-1}(Y)$

If that's what you are asking...
• Oct 31st 2010, 06:46 AM
nerdo
4*(I(Y)-130) = Y

so $I^{-1}(Y)$=4*(Y-130)
• Oct 31st 2010, 06:48 AM
Unknown008
Yep.

Try the other one now.