I FINALLY FOUND HIM BOYS *dies*

For f(x)=2x+3 and g(x)=x^2- 8 find (f+g) (x)

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

The base of a triangle exceeds the height by 9 inches. if the area is 180 square inches, find the length of the base and the height of the triangle.