What number should be added to the expression x2+6x to change it into a perfect square trinomial?

a. 3

b. 6

c. 9

d. 12

Option (c) is correct.

The expression becomes

Step-by-step explanation:

Given expression

We have to find the number that must be added to the given expression so that it change it into a perfect square trinomial.

Consider the given expression

To make it a perfect square trinomial convert the given expression in the form of perfect square

Using the identity

Compare the given expression we have

a = x   ....(1)

⇒ 2ab = 6x  

From (1) , we have

⇒ 2b = 6

⇒ b = 3

Thus, to make perfect square we have to add term ,

That is  

Thus, the expression becomes  

Option (c) is correct.