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.

2a x 2b = (2 x 2) (a x b) = 4ab

The volume of a cylinder is πr²h:

v = πr²h
v = π(3² x 9)
v = 81π

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

a² + 3a - 4 = 0
(a - 1)(a + 4) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (a - 1) or (a + 4) must equal zero:

If (a - 1) = 0, a must equal 1
If (a + 4) = 0, a must equal -4

So the solution is that a = 1 or -4

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).

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