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.

5a - 8a = -3a

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 9 + 1 + 8 + 9
p = 27

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.

8a⁴ + 2a⁴ = 10a⁴

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:

z² - 13z - 8 = -5z + 1
z² - 13z - 8 - 1 = -5z
z² - 13z + 5z - 9 = 0
z² - 8z - 9 = 0

Next, factor the quadratic equation:

z² - 8z - 9 = 0
(z + 1)(z - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z + 1) or (z - 9) must equal zero:

If (z + 1) = 0, z must equal -1
If (z - 9) = 0, z must equal 9

So the solution is that z = -1 or 9

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

a = l x w
a = a x b
a = 1 x 3
a = 3