A monomial contains one term, a binomial contains two terms, and a polynomial contains more than two terms.

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 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.

7a⁶ + 5a⁶ = 12a⁶

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 -36 as well and sum (Inside, Outside) to equal -5. For this problem, those two numbers are -9 and 4. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² - 5y - 36
y² + (-9 + 4)y + (-9 x 4)
(y - 9)(y + 4)

A line segment is a portion of a line with a measurable length. The midpoint of a line segment is the point exactly halfway between the endpoints. The midpoint bisects (cuts in half) the line segment.