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

sa = 2πr² + 2πrh
sa = 2π(1²) + 2π(1 x 8)
sa = 2π(1) + 2π(8)
sa = (2 x 1)π + (2 x 8)π
sa = 2π + 16π
sa = 18π

A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

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 < sign and the answer on the other.

2a + 5 < -9 - 3a
2a < -9 - 3a - 5
2a + 3a < -9 - 5
5a < -14
a < \( \frac{-14}{5} \)
a < -2\(\frac{4}{5}\)

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)(7ab) + (8a²)(4b)
(7 x 7)(a x a x b) + (8 x 4)(a² x b)
(49)(a¹⁺¹ x b) + (32)(a²b)
49a²b + 32a²b
81a²b

When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)