# How do you simplify ( -7+7a)/(21a^2-21)?

May 6, 2018

Factorize
$\frac{- 7 \left(1 - a\right)}{- 21 \left(- {a}^{2} + 1\right)}$
You get
(1(1-a))/(3(1-a^2)
You get
$\frac{1 - a}{3 \left({1}^{2} - {a}^{2}\right)}$
As $1 = {1}^{2}$

By the law of exponents
${a}^{2} - {b}^{2} = \left(a + b\right) \left(a - b\right)$
(1cancel((1-a)))/(3cancel((1-a))(1+a)
You get
$\frac{1}{3 \left(1 + a\right)}$

IF you want to simplify it further it would be ${\left(3 + 3 a\right)}^{- 1}$