将p(2,3)带入
3 = k * 2
k = 1.5
===> y = 1.5x将该直线向上平移3个单位，求平移后的表达式？？向上平移3个单位，经过(2, 6)点，y = 1.5*x + b6 = 1.5*2 + bb = 6-3 =3 y=1.5x+3