the answer is
v=3 or -3/2
show the calculation please!
I'm sure you've gotten this far.
What does "complete the square" mean? We need to add a number to both sides of the equation such that the LHS is a perfect square. My first suggestion is to divide through by 6 to make the coefficient of v^2 one. (This is not necessary, but I find it makes the problem simpler.)
We need to find a number to add to the LHS to make it a perfect square. The only number we can use is the coefficient of the linear term: 3/2. What does that tell us about the number we must add? Check your text and see how far you can get from here.
Here is another approach to completing the square, arrange the equation as:
Multiply through by 4 times the coefficient of the squared term, which is 8 and then add the square of the coefficient of the linear term which is 9:
Can you finish?