Answer:
b=30
a=120
c=50 these is how I figure it out
Answer:
a = -0.3575
Step-by-step explanation:
The points A and D lie on the x-axis, this means that they are the x-intercepts of the parabola, and therefore we can find their location.
The points A and B are located where

This gives


Now given the coordinates of A, we are in position to find the coordinates of the point B. Point B must have y coordinate of y=2 (because the base of the trapezoid is at y=0), and the x coordinate of B, looking at the figure, must be x coordinate of A plus horizontal distance between A and B, i.e

Thus the coordinates of B are:

Now this point B lies on the parabola, and therefore it must satisfy the equation 
Thus

Therefore


When factoring, it's easier to "pick out" the GCF first because it makes it simpler to factor even further. Otherwise, you will be troubled with lots of numbers and variables, so it will just get confusing.