When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

The slope of this line is the change in y divided by the change in x. The endpoints of this line segment are at (-2, -8) and (2, 4) so the slope becomes:

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 21 as well and sum (Inside, Outside) to equal 10. For this problem, those two numbers are 3 and 7. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 10y + 21
y² + (3 + 7)y + (3 x 7)
(y + 3)(y + 7)

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.

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.