The x is the coefficent and every x has a coefficent even if it doesn't have number because the coefficent represent how many x's there are so it is one x plus 6 x and that equal seven x. The x can be anything but one of something plus 6 equals 7.
We can use the vertex form of a quadratic, , to find that . Plugging ordered pairs into g(x), we see that a = 1. For example, for , . Solving for a gives 1.
, to find that 
. Plugging 
ordered pairs into g(x), we see that a = 1. For example, for 
, 
. Solving for a gives 1.