You can only add or subtract monomials that have the same variable and the same exponent. For example, 2a + 4a = 6a and 4a² - a² = 3a² but 2a + 4b and 7a - 3b cannot be combined. However, you can multiply and divide monomials with unlike terms. For example, 2a x 6b = 12ab.

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 45 as well and sum (Inside, Outside) to equal 14. For this problem, those two numbers are 5 and 9. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 14y + 45
y² + (5 + 9)y + (5 x 9)
(y + 5)(y + 9)

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 entire length of this line is represented by AD which is AB + BD:

AD = AB + BD

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)(5ab) + (5a²)(2b)
(5 x 5)(a x a x b) + (5 x 2)(a² x b)
(25)(a¹⁺¹ x b) + (10)(a²b)
25a²b + 10a²b
35a²b