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

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 -11. 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 - 11y + 18
y² + (-9 - 2)y + (-9 x -2)
(y - 9)(y - 2)

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.

(8a)(9ab) - (4a²)(9b)
(8 x 9)(a x a x b) - (4 x 9)(a² x b)
(72)(a¹⁺¹ x b) - (36)(a²b)
72a²b - 36a²b
36a²b

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 x 2b = (4 x 2) (a x b) = 8ab

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

b² + 2b - 15 = 0
(b - 3)(b + 5) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (b - 3) or (b + 5) must equal zero:

If (b - 3) = 0, b must equal 3
If (b + 5) = 0, b must equal -5

So the solution is that b = 3 or -5