The Purplemath Forums

by **MissTracy03** on Mon Aug 09, 2010 2:21 pm

Hello - I need help with the following problem. I was asked to find the inverse of: f(x) = 7x+3 over 8

If I’m doing this correctly, I would first replace f(x) with “y”, then I switched “y” and “x”. I believe my next step would be to multiply both sides by 8, correct? I’m blanking on the process, so I think that would give me 8x = 56x+24 over 64?

Your help is greatly appreciated.

**Sponsor**

by **Martingale** on Mon Aug 09, 2010 5:43 pm

MissTracy03 wrote:Hello - I need help with the following problem. I was asked to find the inverse of: f(x) = 7x+3 over 8

If I’m doing this correctly, I would first replace f(x) with “y”, then I switched “y” and “x”. I believe my next step would be to multiply both sides by 8, correct? I’m blanking on the process, so I think that would give me 8x = 56x+24 over 64?

Your help is greatly appreciated.

$y = \frac{7x+3}{8}$

$x = \frac{7y+3}{8}$

$8\cdot x = 8\cdot\frac{7y+3}{8}$

$8\cdot x = \cancel{8}\cdot\frac{7y+3}{\cancel{8}}$

$8\cdot x = 7y+3$

...

The Purplemath Forums

Inverse of a function: f(x) = 7x+3 over 8

Inverse of a function: f(x) = 7x+3 over 8

Re: Inverse of a function