The equation of a parabola is y=x2–10x+25. write the equation in vertex form.

We must re-write the given equation in vertex form.  "Vertex form" has this appearance:  y-k = a(x-h)^2 (which applies to a vertical parabola).

Important:  Please express "square of x" as x^2, not as x2.

We can re-write y = x^2 - 10x + 25, using "completing the square," as

y = (x-5)^2 + 0.  
Multiply this out to verify that it does indeed equal x^2 - 10x + 25.

Then, in vertex form, the equation of this parabola is y - 0 = 1(x-5)^2.

The vertex (h,k) is at (5,0).