6

4

4

12

3

4

I can't read the last one, sorry.

12*6 = 72 - (3*4) = 60 - (4*5) = 40

<span>Quadrilateral ABCD is a parallelogram because both pairs of opposite sides are parallel.
Slope of a line is defined as the difference in Y divided by the difference in X. It doesn't matter which way you do the subtraction as long as you do it in the same order for both X and Y. So let's calculate the slope of AB
A(-5,1)
B(-2,5)
(1 - 5)/(-5 - (-2)) = -4/-3 = 4/3
Slope BC
B(-2,5)
C(5,3)
(5-3)/(-2-5) = 2/-7 = -2/7
Slope CD
C(5,3)
D(2,-1)
(3-(-1))/(5-2) = 4/3
Slope AD
A(-5,1)
D(2,-1)
(1-(-1))/(-5-2) = 2/-7 = -2/7
So our slopes are 4/3, -2/7, 4/3, and -2/7
Since the slopes of AB and CD are identical, those lines are parallel. And since the slopes of both BC and AD are identical, those 2 lines are also parallel. But since 4/3 * -2/7 = -8/21 which is NOT -1, that means that lines AB and BC are NOT perpendicular, so you don't have a rectangle. But you do have a parallelogram because both pairs of opposite sides are parallel.</span>

Hey there!

This is **true**.

A quadratic equation must be in this form or any other quadratic equation form and must have the squared term. These all need to be real numbers, and it would not work if they weren't. A cannot be zero because if it was the squared term would not be there and therefore it would not be a quadratic equation.

Hope this helps!