Question

How do you factor by grouping `224az+56ac-84yz-21yc`?

Answer 1

First notice that all the coefficients are divisible by 7, so let's separate out that factor first...

`224az+56ac-84yz-21yc`

`= 7(32az+8ac-12yz-3yc)`

`= 7((32az+8ac)-(12yz+3yc))`

`= 7(8a(4z+c)-3y(4z+c))`

`= 7(8a-3y)(4z+c)`