A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.

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.

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

a² + 3a + 2 = 0
(a + 1)(a + 2) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (a + 1) or (a + 2) must equal zero:

If (a + 1) = 0, a must equal -1
If (a + 2) = 0, a must equal -2

So the solution is that a = -1 or -2

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

The coordinate grid is composed of a horizontal x-axis and a vertical y-axis. The center of the grid, where the x-axis and y-axis meet, is called the origin.