Solve $LaTeX: \displaystyle x^{2} - 5 x + 4=0$

Since $LaTeX: \displaystyle a=1$ we need to find factors of $LaTeX: \displaystyle 4$ that add up to $LaTeX: \displaystyle -5$ . The factors are $LaTeX: \displaystyle -1$ and $LaTeX: \displaystyle -4$ . This gives $LaTeX: \displaystyle (x - 1)(x - 4)=0$ . The solutions are $LaTeX: \displaystyle x = 1$ and $LaTeX: \displaystyle x = 4$