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.

(3a)(8ab) - (7a²)(4b)
(3 x 8)(a x a x b) - (7 x 4)(a² x b)
(24)(a¹⁺¹ x b) - (28)(a²b)
24a²b - 28a²b
-4a²b

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

c² - 15c + 54 = 0
(c - 6)(c - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c - 6) or (c - 9) must equal zero:

If (c - 6) = 0, c must equal 6
If (c - 9) = 0, c must equal 9

So the solution is that c = 6 or 9

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:

a² - 9a + 38 = 3a + 3
a² - 9a + 38 - 3 = 3a
a² - 9a - 3a + 35 = 0
a² - 12a + 35 = 0

Next, factor the quadratic equation:

a² - 12a + 35 = 0
(a - 5)(a - 7) = 0

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

If (a - 5) = 0, a must equal 5
If (a - 7) = 0, a must equal 7

So the solution is that a = 5 or 7

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

The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 5cm + 15cm + 11cm = 31cm