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.

9a⁹ + 5a⁹ = 14a⁹

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 + 7)(y - 1)
(y x y) + (y x -1) + (7 x y) + (7 x -1)
y² - y + 7y - 7
y² + 6y - 7

The area of a rectangle is equal to its length x width:

a = l x w
a = a x b
a = 3 x 8
a = 24

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 - z = -8a + 4z - 3
5a = -8a + 4z - 3 + z
5a + 8a = 4z - 3 + z
13a = 5z - 3
a = \( \frac{5z - 3}{13} \)
a = \( \frac{5z}{13} \) + \( \frac{-3}{13} \)
a = \(\frac{5}{13}\)z - \(\frac{3}{13}\)

The formula for area is πr². Radius is circle \( \frac{diameter}{2} \):

r = \( \frac{d}{2} \)
r = \( \frac{10}{2} \)
r = 5
a = πr²
a = π(5²)
a = 25π