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.

7a x 3b = (7 x 3) (a x b) = 21ab

The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(6²) + 2π(6 x 9)
sa = 2π(36) + 2π(54)
sa = (2 x 36)π + (2 x 54)π
sa = 72π + 108π
sa = 180π

You can only add or subtract monomials that have the same variable and the same exponent. For example, 2a + 4a = 6a and 4a² - a² = 3a² but 2a + 4b and 7a - 3b cannot be combined. However, you can multiply and divide monomials with unlike terms. For example, 2a x 6b = 12ab.

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

-5z + 3 = \( \frac{z}{-8} \)
-8 x (-5z + 3) = z
(-8 x -5z) + (-8 x 3) = z
40z - 24 = z
40z - 24 - z = 0
40z - z = 24
39z = 24
z = \( \frac{24}{39} \)
z = \(\frac{8}{13}\)

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

c² - 10c + 25 = 0
(c - 5)(c - 5) = 0

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

If (c - 5) = 0, c must equal 5

So the solution is that c = 5