To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

2a + 7a = 9a

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 + 3)(y + 1)
(y x y) + (y x 1) + (3 x y) + (3 x 1)
y² + y + 3y + 3
y² + 4y + 3

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

3a⁵ - 8a⁵ = -5a⁵

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.

(9a)(7ab) + (2a²)(9b)
(9 x 7)(a x a x b) + (2 x 9)(a² x b)
(63)(a¹⁺¹ x b) + (18)(a²b)
63a²b + 18a²b
81a²b

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.