Ask a math question: how much is the square of equation 2Y + 3 = 7Y after formula 2 (Y-7 / 4)?

Ask a math question: how much is the square of equation 2Y + 3 = 7Y after formula 2 (Y-7 / 4)?

2y^2+3=7y
2y^2-7y+3=0
2[y^2-7/2y+(7/4)^2]=2*(7/4)^2-3
2(y-7/4)^2=25/8
..