# Which value must be added to the expression x^{2} + 12x to make it a perfect-square trinomial?

6, 36, 72,144

**Solution:**

x^{2} + 12x [Given]

The standard form of a perfect square trinomial is

(x - a)^{2} = x^{2} - 2ax + a^{2}

In the given equation add c as the value which must be added

x^{2} + 12x + c

By equating it with the standard form

12x = - 2ax ----> (1)

c = a^{2 }----> (2)

Solving these equations for a and c respectively, we get

12x = - 2ax

a = 12/-2

a = -6

c = (-6)^{2} = 36

Here

(x - (-6))^{2} = x^{2} + 12x + 36

Therefore, the value which must be added is 36.

## Which value must be added to the expression x^{2} + 12x to make it a perfect-square trinomial?

6, 36, 72, 144

**Summary: **

The value which must be added to the expression x^{2} + 12x to make it a perfect-square trinomial is 36.