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 factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 18 as well and sum (Inside, Outside) to equal 11. For this problem, those two numbers are 2 and 9. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 11y + 18
y² + (2 + 9)y + (2 x 9)
(y + 2)(y + 9)

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

3a² + 9a² = 12a²

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.

(8a)(7ab) + (8a²)(8b)
(8 x 7)(a x a x b) + (8 x 8)(a² x b)
(56)(a¹⁺¹ x b) + (64)(a²b)
56a²b + 64a²b
120a²b

To solve this equation, isolate the variable for which you are solving (a) on one side of the equation and put everything else on the other side.

-5a + 8x = 6a + 8x + 8
-5a = 6a + 8x + 8 - 8x
-5a - 6a = 8x + 8 - 8x
-11a = + 8
a = \( \frac{ + 8}{-11} \)
a = \( \frac{}{-11} \) + \( \frac{8}{-11} \)
a = x - \(\frac{8}{11}\)