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.

9a x 2b = (9 x 2) (a x b) = 18ab

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 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:

x² + 2x - 79 = 2x + 2
x² + 2x - 79 - 2 = 2x
x² + 2x - 2x - 81 = 0
x² - 81 = 0

Next, factor the quadratic equation:

x² - 81 = 0
(x - 9)(x + 9) = 0

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

If (x - 9) = 0, x must equal 9
If (x + 9) = 0, x must equal -9

So the solution is that x = 9 or -9

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

a = l x w
a = a x b
a = 3 x 4
a = 12