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

c² - 2c - 8 = 0
(c + 2)(c - 4) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c + 2) or (c - 4) must equal zero:

If (c + 2) = 0, c must equal -2
If (c - 4) = 0, c must equal 4

So the solution is that c = -2 or 4

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) + (9a²)(9b)
(8 x 9)(a x a x b) + (9 x 9)(a² x b)
(72)(a¹⁺¹ x b) + (81)(a²b)
72a²b + 81a²b
153a²b

A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

y² + 3y - 38 = 5y - 3
y² + 3y - 38 + 3 = 5y
y² + 3y - 5y - 35 = 0
y² - 2y - 35 = 0

Next, factor the quadratic equation:

y² - 2y - 35 = 0
(y + 5)(y - 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y + 5) or (y - 7) must equal zero:

If (y + 5) = 0, y must equal -5
If (y - 7) = 0, y must equal 7

So the solution is that y = -5 or 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 - 1)(y - 1)
(y x y) + (y x -1) + (-1 x y) + (-1 x -1)
y² - y - y + 1
y² - 2y + 1