Solve $LaTeX: \displaystyle x^{2} - 19 x + 90=0$

Since $LaTeX: \displaystyle a=1$ we need to find factors of $LaTeX: \displaystyle 90$ that add up to $LaTeX: \displaystyle -19$ . The factors are $LaTeX: \displaystyle -10$ and $LaTeX: \displaystyle -9$ . This gives $LaTeX: \displaystyle (x - 10)(x - 9)=0$ . The solutions are $LaTeX: \displaystyle x = 10$ and $LaTeX: \displaystyle x = 9$