Math basics › Algebra basics
Distributing
Everything inside, every time
a(b + c) = ab + ac. If there are three terms in the bracket, you produce three terms.
A minus in front flips everything
−(x − 5) = −x + 5. The sign applies to every term, not just the first.
Two brackets
(a + b)(c + d) = ac + ad + bc + bd. Four products, always — that is all FOIL means.