Question

Decide what number must be added to each binomial to make a perfect square trinomial. Show your

work.
X^2-21x

Answer 1

110.25

Explanation:

Consider the square ...

(x +a)^2 = x^2 +2ax +a^2

The added constant (a^2) is the square of half the x-coefficient:

a^2 = ((2a)/2)^2

__

The added constant needs to be the square of half the x-coefficient:

c = (-21/2)^2 = 441/4 = 110.25

__

x^2 -21x +110.25 = (x -10.5)^2