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.

4a⁷ - 8a⁷ = -4a⁷

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 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:

y² - 26 = -y + 4
y² - 26 - 4 = -y
y² + + y - 30 = 0
y² + y - 30 = 0

Next, factor the quadratic equation:

y² + y - 30 = 0
(y - 5)(y + 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y - 5) or (y + 6) must equal zero:

If (y - 5) = 0, y must equal 5
If (y + 6) = 0, y must equal -6

So the solution is that y = 5 or -6

A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)