Solve $LaTeX: \displaystyle 5 x^{2} + 5 x - 100=0$

Since the GCF is $LaTeX: \displaystyle 5$ we need we factor out the GCF to get $LaTeX: \displaystyle 5(x^{2} + x - 20)$ . This is now a pq method factoring. The factors of $LaTeX: \displaystyle -20$ that add up to $LaTeX: \displaystyle 1$ are $LaTeX: \displaystyle 5$ and $LaTeX: \displaystyle -4$ . This gives $LaTeX: \displaystyle 5(x + 5)(x - 4)=0$ . The solutions are $LaTeX: \displaystyle x = -5$ and $LaTeX: \displaystyle x = 4$