Answer:
36
Explanation:
Compare what you have to the square ...
(a +b)^2 = a^2 +2ab +b^2
Your "a" is √(25x^2) = 5x
Your "2ab" is -60x. Since you know "a", you can find "b".
2ab = -60x
2(5x)b = -60x . . . . . . . substitute for "a"
b = -60x/(10x) = -6
Then the missing term is b^2 = (-6)^2 = 36.
Your trinomial is ...
25x^2 -60x +36