在一定范围内，某种产品的购买量y吨与单价x元之间满足一次函数关

在一定范围内，某种产品的购买量y吨与单价x元之间满足一次函数关系，如果购买1 000吨，每吨为800元；购买2 000吨，每吨为700元.一客户购买400吨单价应该是( )

A.820元 B.840元 C.860元 D.880元

答案

思路解析：设y=kx+b，由

∴∴y=-10x+9 000.

∴x=.当y=400时，x=860元.故选C.

答案：C

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在一定范围内，某种产品的购买量y吨与单价x元之间满足一次函数关

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