Respuesta :

The third term should be 25 making the trinomial a perfect square of (x-5)^2

An easy way to find this last term is take half of the middle term's coefficient and square that.
Take 1/2 the coefficient of x and square it
(1/2) (-10) = -5 
(-5)2 = 25

ANSWER 25 TO COMPLETE THE SQUARE x^2 - 10 x +25