you take b which is 6 and make it negative, then you take a and multiply it by 2, which is 6. you then take the 2 numbers and put the -b over 2a in this formula -b/2a giving you -1 as your x value
after you do that, you input the -1 into the equation as x and the value you get out of that (-12) is the y value of the vertex
