5x+x^2>100

Here's a graph of the solution

The graph of y = 5x + x² is in red

The graph of y = 100 is in blue

The solution is both segments of the "red" graph that lie "above" - but not touching - the "blue" graph

In interval notation, the solution set lies in two intervals...(-∞, -12.81)  and  (7.81, ∞)