2x^2 = 3x - 7

I understand up to a certain point ;

1. 2x^2 = 3x - 7 ( subtracting 3x )

2. 1/2(2x^2 - 3x ) = 1/2(-7) ( multiplying by 1/2 to make the x^2 - coefficent 1)

3. x^2 - 3/2x = -7/2 ( miltiplying and simplifying )

according to the text it says

x^2 - 3/2x + 9/16 = -7/2 + 9/16 i don't understand how they

got that result