1) To find out the inverse function, assuming this function admits one, let's proceed with these steps:
y=8x -7 Swap x for y
x = 8y -7 Let's isolate y on the left side subtracting 8y from both sides
x -8y = -7 Add -x to both sides
-8y = -7 -x Divide both sides by -8
y =7/8 +x/8 Write the proper notation
[tex]f^{-1}(x)\text{ =}\frac{x}{8}+\frac{7}{8}[/tex]
2) And that's the answer
