# How do you factor y^2 + 0.2y - 0.15?

Aug 28, 2016

${y}^{2} + 0.2 y - 0.15 = \left(y + 0.5\right) \left(y - 0.3\right)$

#### Explanation:

Note that $5 \cdot 3 = 15$ and $5 - 3 = 2$. We use this later...

If we let $x = 0.1$ then:

${y}^{2} + 0.2 y - 0.15$

$= {y}^{2} + 2 x y - 15 {x}^{2}$

$= \left(y + 5 x\right) \left(y - 3 x\right)$

$= \left(y + 0.5\right) \left(y - 0.3\right)$