# How do you factor x²-x-20?

${x}^{2} - x - 20 = \left(x - 5\right) \left(x + 4\right)$
Find a pair of factors of $20$ that differ by $1$. The pair $5 , 4$ works, so we find:
${x}^{2} - x - 20 = \left(x - 5\right) \left(x + 4\right)$