Question

How do you multiply `12a(a + b)(a + -1b)`?

Answer 1

`-1b=-b`
You get
`12a(a+b)(a-b)`
The identity literally is:
`(a+b)(a-b)=a^2-b^2`
You get
`12a(a^2-b^2)`
You should know that:
`12a(a^2-b^2)!=12axxa^2-b^2`
Distribute it,
`a(x+- xx div y)=axx x +-xx div axxy`
The `+-xxdiv` means it could be anything in between
By using distributive property
`12axxa^2-12axxb^2`
Remember,
`a^mxxa^n=a^(m+n)`
`12(a^(1+2)) - 12ab^2`
You get
`12a^3-12ab^2`