To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(5a)(5ab) + (4a²)(8b)
(5 x 5)(a x a x b) + (4 x 8)(a² x b)
(25)(a¹⁺¹ x b) + (32)(a²b)
25a²b + 32a²b
57a²b

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 1 + 6 + 3 + 6
p = 16

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y + 2)(y - 9)
(y x y) + (y x -9) + (2 x y) + (2 x -9)
y² - 9y + 2y - 18
y² - 7y - 18

A cube is a rectangular solid box with a height (h), length (l), and width (w). The volume is h x l x w and the surface area is 2lw x 2wh + 2lh.