X2 + 4x – 9

Can someone give me step by explanation and write the equation in vertex form?

Step-by-step explanation:

You can do it by completing the square:

We add 4 to complete the square but we also subtract 4 because we don't  want to change the equation (+4-4=0 so it doesn't change anything in equation)

so we get:

The vertex is:  (-2, -13)

(because x+2=x-h  ⇒h=-2 and  +q=-13 ⇒ q=-13)

We can also use that:

  for  

bn,mn,n.vn.

step-by-step explanation: