Given:
The equation of a parabola is:

To find:
The vertex of the graph of the given equation by using a graphing calculator.
Solution:
We have,

By using the graphing calculator, draw the graph of the given equation as shown below.
From the below graph it is clear that the function is maximum at point (1.75,10.125).
So, the vertex of the given equation is (1.75,10.125).
Therefore, the correct option is c.