# How do you factor 21m^2 - 57m + 30?

Jun 16, 2015

Factor: $y = 21 {m}^{2} - 57 m + 30$

#### Explanation:

$y = 3 \left(7 {m}^{2} - 19 m + 10\right)$

To factor the trinomial in parentheses, i use the new AC Method (Google, Yahoo Search)
Converted trinomial: ${m}^{2} - 19 m + 70.$ Roots have same sign. Compose factor pairs of a.c = 70 -> (2, 35)(5, 14). This sum is 19 = -b.
Then, p' = -5 and q' = -14. Next,$p = - \frac{5}{7}$ and $q = - \frac{14}{7} = - 2.$

Factored form: $y = 3 \left(7 m - 5\right) \left(m - 2\right)$