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).

The formula for area is πr²:

a = πr²
a = π(4²)
a = 16π

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.

5a x 5b = (5 x 5) (a x b) = 25ab

A parallelogram is a quadrilateral with two sets of parallel sides. Opposite sides (a = c, b = d) and angles (red = red, blue = blue) are equal. The area of a parallelogram is base x height and the perimeter is the sum of the lengths of all sides (a + b + c + d).

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:

b² + 12b + 52 = -2b + 4
b² + 12b + 52 - 4 = -2b
b² + 12b + 2b + 48 = 0
b² + 14b + 48 = 0

Next, factor the quadratic equation:

b² + 14b + 48 = 0
(b + 6)(b + 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (b + 6) or (b + 8) must equal zero:

If (b + 6) = 0, b must equal -6
If (b + 8) = 0, b must equal -8

So the solution is that b = -6 or -8