Given the function
[tex]f(x)=-8x+4[/tex]
The inverse of the function is calculated by changing f(x) to y and making x the subject of the formula as follows:
[tex]y=-8x+4 \\ \\ y-4=-8x \\ \\ x= \frac{y-4}{-8} [/tex]
We now change back the variables to get the function in the form of inverse function as follows:
[tex]f^{-1}(x)=\frac{x-4}{-8}[/tex]
Comparing this with Talib's work, we can see that he is correct except for the last line where he did not change the variable y back to x.
Therefore, the last line of his work made his inverse not to be correct.
