The first two terms of a trinomial are given. What number must be added to make the expression a binomial square?

a) x^2 - 10x+____
b) x^2 + 11x+____

Question

The first two terms of a trinomial are given. What number must be added to make the expression a binomial square?

a) x^2 - 10x+____
b) x^2 + 11x+____

anonymous · Answer

For the first one, notice 

a =1 

b = -10

To complete the square we need

(b/2)^2

Using the order of operations

b = -10

b/2 = -5

(b/2)^2 = 25  <------------  answer

Can you try the second one?

mertsj · Answer

1/2 of 10 = 5 and 5^2 = 25 so add 5 to the first one

mertsj · Answer

1/2 of 11 is 11/2 and (11/2)^2 = 121/4.  So add 121/4 to the second one.

anonymous · Answer

so do I divide the second number by 2?

10x and 11x

anonymous · Answer

yes, and then take that answer and times it by itself

anonymous · Answer

thx guys

mertsj · Answer

Not the x, just the coefficient

anonymous · Answer

yeah ok