Please repost with the image turned 90o.
It appears that Halls has a slight typo it should be \(\large 1{\color{blue}+}e^{3x-4}\) ...................................typo fixedIF \(\displaystyle f(x)= 1+ e^{5- x}\) for \(\displaystyle 0< x\le b\) and
\(\displaystyle f(x)= 1- e^{3x- 4}\) for \(\displaystyle b< x\le 5\)