The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 4 x 7 = \( \frac{28}{2} \) = 14

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

z² + 8z + 7 = 0
(z + 1)(z + 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z + 1) or (z + 7) must equal zero:

If (z + 1) = 0, z must equal -1
If (z + 7) = 0, z must equal -7

So the solution is that z = -1 or -7

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.

6a + 4a = 10a

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

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 - 9)(y + 2)
(y x y) + (y x 2) + (-9 x y) + (-9 x 2)
y² + 2y - 9y - 18
y² - 7y - 18