# How do you solve a^2+11a=-18?

Jan 19, 2017

$a = - 2 , \mathmr{and} - 9$

#### Explanation:

${a}^{2} + 11 a = - 18$, add $18$ to both sides,

${a}^{2} + 11 a + 18 = - 18 + 18$

${a}^{2} + 11 a + 18 = 0$, and now we try to factorize this expression,

$\left(a + 2\right) \left(a + 9\right) = 0$,

you just have to practise playing around with these expressions to do this. We knew that the product of the real numbers must be $18$, and that the sum of their product with $a$ must be $11 a$. The factors $2$ and $9$ fulfills these criteria.