A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.

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 + 3z - 12 = -4z - 4
z² + 3z - 12 + 4 = -4z
z² + 3z + 4z - 8 = 0
z² + 7z - 8 = 0

Next, factor the quadratic equation:

z² + 7z - 8 = 0
(z - 1)(z + 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z - 1) or (z + 8) must equal zero:

If (z - 1) = 0, z must equal 1
If (z + 8) = 0, z must equal -8

So the solution is that z = 1 or -8

The slope of this line is the change in y divided by the change in x. The endpoints of this line segment are at (-2, 1) and (2, -7) so the slope becomes:

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 25° - 68° = 87°

So, d° = 68° + 87° = 155°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 25° = 155°

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.

(3a)(4ab) + (9a²)(3b)
(3 x 4)(a x a x b) + (9 x 3)(a² x b)
(12)(a¹⁺¹ x b) + (27)(a²b)
12a²b + 27a²b
39a²b