Question

Let f(x)=(x+7)/(x+5). inverse f-1(-3)=...
Reiny
let y = (x+7)/(x+5)

to form the inverse, interchange the x and y variables, thus

x = (y+7)/(y+5)
xy + 5x = y + 7
xy - y = 7 - 5x
y(x-1) = 7-5x
y = (7-5x)/(x-1)

so f<sup>-1</sup>(x) = (7-5x)/(x-1)
and
f<sup>-1</sup>(-3) = (7-5(-3))/((-3)-1)
= 22/-4 = -11/2































<3
f-1(-3) = (5-7(-3))/((-3)-1)
= 26/-4 = -13/2

thanks!
Reiny
nope!

checking :
subbing my answer of -11/2 back in the original function yields -3
Your answer of -13/2 does not.