Question

What integer needs to be added to the expression to create a perfect square? x^2 + 30x
A. 15
B. 30
C. 225
D. 900

Answer 1

Take half the coefficient of the linear x term (30) and square it. That is the integer that needs to be added.

Answer 2

A

Answer 3

No. That is the half of the 30. Now, square 15 to get the integer you need to add. What is the square of 15?

Answer 4

15^2 = 15 * 15 = ?

Answer 5

225

Answer 6

Yes. Let's check.

x^2 + 30x + 225 = (x + 15)(x + 15) = (x + 15)^2 which is a perfect square trinomial.