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 circumference is circle diameter x π:

c = πd
c = 6π

You need to find the value of a so solve the first equation in terms of x:

5a + x = 9
x = 9 - 5a

then substitute the result (9 - 5a) into the second equation:

-2a - 5(9 - 5a) = 2
-2a + (-5 x 9) + (-5 x -5a) = 2
-2a - 45 + 25a = 2
-2a + 25a = 2 + 45
23a = 47
a = \( \frac{47}{23} \)
a = 2\(\frac{1}{23}\)

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

b² + 9b + 8 = 0
(b + 1)(b + 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (b + 1) or (b + 8) must equal zero:

If (b + 1) = 0, b must equal -1
If (b + 8) = 0, b must equal -8

So the solution is that b = -1 or -8

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y - 1)(y - 8)
(y x y) + (y x -8) + (-1 x y) + (-1 x -8)
y² - 8y - y + 8
y² - 9y + 8