変化の割合，切片
を答えよう
y=[1/2]x+3
  [1/2]　+3
y=2x-5
 2  -5
y=-3x+2
 -3  +2
y=[2/5]x+4
 [2/5]  +4
y=-[3/5]x-5
 -[3/5]  -5
y=-[4/3]x+1
 -[4/3]  +1
y=-5x-[2/3]
 -5  -[2/3]
y=[1/2]x-[3/2]
 [1/2]  -[3/2]
y=-[2/3]x+[1/3]
 [2/3]  [1/3]