Question

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

Answer 1

Factorize
`(-7(1-a))/(-21(-a^2+1))`
You get
`(1(1-a))/(3(1-a^2)`
You get
`(1-a)/(3(1^2-a^2))`
As `1=1^2`

By the law of exponents
`a^2-b^2=(a+b)(a-b)`
`(1cancel((1-a)))/(3cancel((1-a))(1+a)`
You get
`1/(3(1+a))`

IF you want to simplify it further it would be `(3+3a)^(-1)`