# How do you factor 1 - 4y^2?

Mar 3, 2018

$\left(1 - 2 y\right) \left(1 + 2 y\right)$

#### Explanation:

$\text{this is a "color(blue)"difference of squares}$

•color(white)(x)a^2-b^2=(a-b)(a+b)

$\text{here "a=1" and } b = 2 y$

$\Rightarrow 1 - 4 {y}^{2} = \left(1 - 2 y\right) \left(1 + 2 y\right)$

Mar 3, 2018

$\left(1 + 2 y\right) \left(1 - 2 y\right)$

#### Explanation:

$\textcolor{b l u e}{1 - 4 {y}^{2}}$

$\implies \textcolor{b l u e}{{\left(1\right)}^{2} - {\left(2 y\right)}^{2}}$

We have an identity for $\textcolor{g r e e n}{{a}^{2} - {b}^{2}}$ which is equal to $\textcolor{g r e e n}{\left(a + b\right) \left(a - b\right)}$.

So , $\textcolor{red}{{\left(1\right)}^{2} - {\left(2 y\right)}^{2}}$

$\implies \textcolor{red}{\left(1 + 2 y\right) \left(1 - 2 y\right)}$