Question 186795
That is the correct answer. Maybe the book uses different notation? You could replace the 'y' with *[Tex \LARGE f^{-1}\left(x\right)] to get



*[Tex \LARGE f^{-1}\left(x\right)=\frac{1}{2}x+\frac{3}{2}] 



There could be a typo, or you might have written the wrong equation. Either way, double check the book or ask your teacher.