To find the height, you would first multiply the length and width. You would get 56. Set that equal to 280 with an x to represent height. 280=56x. Then, you would divide 56 on both sides which leaves you with 5=x. So, your height would be 5 meters.
The vertex of the function is at x = -3/2. We cannot find the y value with an incomplete equation.
To find the x value of a vertex, we use the equation -b/2a, in which a is equal to the coefficient of x^2 (in this case 1) and b is equal to the coefficient of x (in this case 3).
-b/2a
-3/2(1)
-3/2
This gives us that value. To find the y value, you would plug this into the equation. Since this equation is not complete, you cannot do that yet.