What number should be added??
x^(2)-4x

My results is 4.. But it is -4 o 4??
I am confused!!
Thx!

Question

What number should be added??
x^(2)-4x

My results is 4.. But it is -4 o 4??
I am confused!!
Thx!

directrix · Answer

I assume you are making a perfect square trinomial. If so, you could write the two possible trinomials and determine which one might factor as a square.

x^(2) -4x + 4 =

and then 

x^(2 ) -4x - 4 =

How did you get the 4? That may be a clue as to whether the last term is 4 or -4.

directrix · Answer

What do you think the answer is?  4 or -4? I'll attempt to factor and see what happens.