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 -18 as well and sum (Inside, Outside) to equal -7. For this problem, those two numbers are -9 and 2. Then, plug these into a set of binomials using the square root of the First variable (y²):

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

To factor a quadratic expression, apply the FOIL (First, Outside, Inside, Last) method in reverse.

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

An equation is two expressions separated by an equal sign. The key to solving equations is to repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(1²) + 2π(1 x 9)
sa = 2π(1) + 2π(9)
sa = (2 x 1)π + (2 x 9)π
sa = 2π + 18π
sa = 20π