(1)y=0.4x+0.3(26-x)+0.5(25-x)+0.2[23-(26-x)]
y=-0.2x+19.7 (0<=x<=26)
(2)将y<=15代入
15<=-0.2x+19.7
0.2x<=4.7
x>=23.5
因为前面 (0<=x<=26)
所以x=24 x=25 x=26 三种
甲地需要25台,乙地需23台,故3<=X=<25,故x只能为:24,25两种情况
(1)y=0.4x+0.5(26-x)+0.5(25-x)+0.2[23-(26-x)] (0<=x<=26)且x是正整数。
(2)y<=15解不等式可得x>24.75 有x=25,x=26两种
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nan