(ax)(bx) = (ab)x^2
Multiplying Binomials—FOIL
Classic Factorables
Factor common to all terms:
ax + ay = a(x + y)
Difference of squares:
a^2 − b^2 = (a − b)(a + b)
Square of binomial:
a^2 + 2ab + b^2 = (a + b)^2
Quadratic Formula
If ax^2 + bx + c = 0, then .
Inequalities and Absolute Value
For all n > 0,
(a + b)(c + d) = ?
First = ac
Outer = ad
Inner = bc
Last = bd
Product = ac + ad + bc + bd