设y+3=kx带入 X=2时Y=77+3＝2kk＝5所以是Y+3=5XY=5X-3x=-1/2y=5x-1/2-3=-5.5
假设Y+3=aX x=2时y=7a=5y+3=5xy=5x-3x=-1/2代入y=-5.5
