Question: 
Write a function to find the vertex of a parabola.


Model's Code:
def parabola_vertex(a, b, c):
    x_vertex = -b / (2 * a)
    y_vertex = a * x_vertex**2 + b * x_vertex + c
    return (x_vertex, y_vertex)



Sample Correct Code:
def parabola_vertex(a, b, c): 
  vertex=(((-b / (2 * a)),(((4 * a * c) - (b * b)) / (4 * a))))
  return vertex


Asserts:
assert parabola_vertex(5,3,2)==(-0.3, 1.55)
assert parabola_vertex(9,8,4)==(-0.4444444444444444, 2.2222222222222223)
assert parabola_vertex(2,4,6)==(-1.0, 4.0)


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 153 of 974: 111/153 (72.54901960784314%): success