What is the distributive law?
a(b+c) = ab + ac
In the expression 12(x+18), what do we call the number 12?
12 is the coefficient of the number in brackets (or parentheses).
(a + b)(c + d) =
(ac + ad + bc + bd)
(a + b)(a - b) =
a2-b2
(a + b)2 =
a2 + 2ab + b2