A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

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

a = l x w
a = a x b
a = 8 x 3
a = 24

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.

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:

c² - 10c - 14 = -2c - 5
c² - 10c - 14 + 5 = -2c
c² - 10c + 2c - 9 = 0
c² - 8c - 9 = 0

Next, factor the quadratic equation:

c² - 8c - 9 = 0
(c + 1)(c - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c + 1) or (c - 9) must equal zero:

If (c + 1) = 0, c must equal -1
If (c - 9) = 0, c must equal 9

So the solution is that c = -1 or 9

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.