(1)甲两次购买粮食共需付粮款(100x+100y)元,乙两次共购买 (
100
x +
100
y ) kg粮食.
q 1=
100x+100y
2×100 =
x+y
2 ,
q 2=100×2÷(
100
x +
100
y )=200÷
100x+100y
xy =
2xy
x+y .
(2)q 1-q 2=
x+y
2 -
2xy
x+y =
(x-y) 2
2(x+y) >0 ,故乙的购粮方式合算.
(1)甲两次购买粮食共需付粮款(100x+100y)元,乙两次共购买 (
100
x +
100
y ) kg粮食.
q 1=
100x+100y
2×100 =
x+y
2 ,
q 2=100×2÷(
100
x +
100
y )=200÷
100x+100y
xy =
2xy
x+y .
(2)q 1-q 2=
x+y
2 -
2xy
x+y =
(x-y) 2
2(x+y) >0 ,故乙的购粮方式合算.