What is the missing constant term in the perfect square that starts with x^2+6xx 2 +6xx, start superscript, 2, end superscript, plus, 6, x ?

For this case we have the following polynomial:
 x ^ 2 + 6x
 The missing value to complete the square is given by:
 x ^ 2 + 6x + (6/2) ^ 2
 Rewriting we have:
 x ^ 2 + 6x + (3) ^ 2
 x ^ 2 + 6x + 9
 Then, completing the square we have:
 (x + 3) ^ 2
 
 the missing constant term in the perfect square is:
 9

)because it's going in order of the math sign