The graph of a quadratic function (a parabola) has an axis of symmetry x = 4, and passes
through the point (7.3,5)

y = (x - 4)^2 + 5.89

Step-by-step explanation:

The x-coordinate of the vertex is 4, and x = 4 is the axis of symmetry.  

The general vertex equation of a parabola is

y = a(x - h)^2 + k, where the vertex is (h, k) and a is a constant coefficient, not yet known.

We know that this parabola passes through the point (7.3, 5), and so we can substitute 7.3 for x and 5 for y in the above equation, obtaining:

5 = a(x - 4)^2 + k

Let's assume that a = 1.  Then

5 = (7.3 - 4)^2 + k.

Simplifying, we get

5 = 3.3^2 + k, or 5 = 10.89 + k.  Then k = -5.89, and the equation is then

y = (x - 4)^2 + 5.89

expression #3 is not equivalent. the others are.