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 28 as well and sum (Inside, Outside) to equal 11. For this problem, those two numbers are 4 and 7. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 11y + 28
y² + (4 + 7)y + (4 x 7)
(y + 4)(y + 7)

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

The Pythagorean theorem defines the relationship between the side lengths of a right triangle. The length of the hypotenuse squared (c²) is equal to the sum of the two perpendicular sides squared (a² + b²): c² = a² + b² or, solved for c, \(c = \sqrt{a + b}\)

The area of a parallelogram is equal to its length x width:

a = l x w
a = a x b
a = 5 x 9
a = 45

To solve this equation, 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.)

-6b(b - y)
-6(-9)(-9 + 3)
-6(-9)(-6)
(54)(-6)
-324