(a+b) ² = a ² + 2ab + b ²

(a+b)(c+d) = ac + ad + bc + bd

a ² - b ² = (a+b)(a-b) (Difference of squares)

a ³ b ³ = (a b)(a ² ab + b ²) (Sum and Difference of Cubes)

x ² + (a+b)x + ab = (x + a)(x + b)

if ax ² + bx + c = 0 then x = ( -b (b ² - 4ac) ) / 2a (Quadratic Formula)