J=6
Simply get j by itself by adding 3 to both sides.
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


There is no solution. if you are using the two equations to solve for y and x.
you can plug one equations into the other.
substituting one of the y gives...
3(x+4)=3(x-4)
÷ both sides by 3 gives x+4=x-4
get x on one side and numbers on the other
x-x =4+4
and x-x will give you a 0 for the left side
therefore 0 = 4+4.. not true.