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.

(4a)(2ab) - (2a²)(7b)
(4 x 2)(a x a x b) - (2 x 7)(a² x b)
(8)(a¹⁺¹ x b) - (14)(a²b)
8a²b - 14a²b
-6a²b

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 + 6)(y - 2)
(y x y) + (y x -2) + (6 x y) + (6 x -2)
y² - 2y + 6y - 12
y² + 4y - 12

A line on the coordinate grid can be defined by a slope-intercept equation: y = mx + b. For a given value of x, the value of y can be determined given the slope (m) and y-intercept (b) of the line. The slope of a line is change in y over change in x, \({\Delta y \over \Delta x}\), and the y-intercept is the y-coordinate where the line crosses the vertical y-axis.

The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 7 + 4 + 3 + 6
p = 20