80. Given the function $y=2 x+3, x \in[-1.5 ; 1]$. Find the function that is the inverse of the given one.
Solution. Solving the given equation for $x$, we have $2 x=$ $=y-3$, from which $x=0.5 y-1.5$. Transitioning to conventional notation, i.e., replacing $x$ with $y$ and $y$ with $x$ in the last equation, we obtain the inverse function: $y=0.5 x-1.5, x \in[0,5]$.

In Fig. 79, the graphs of the given function and its inverse are shown, as well as the line $y=x$, relative to which the graphs of these functions are symmetric.