For if these increases of income or utility are reduced to being infinitesimal, one can use both the symbolism and the powerful manipulations of the differential calculus.

因为，如果这些收入或效用的增加可以化为无穷小，那我们既能使用符号表示，也能利用微分学强大的操作了。

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Some firms have adopted “differential pricing” schemes that use formulas, based on average income per head, to set lower prices in poor countries.

一些公司已经在采用依据人均收入区别定价的方法向贫穷国家提供价格较低的药品。

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SRHMS can also discriminate that self rated health is significantly differential in different people, age, family income per person, educational level and profession and residence.

SRHMS能够反映不同人群，不同年龄，不同家庭人均收入，不同文化程度，不同职业和不同住地评价者间自测健康的差异。

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It's entirely arbitrary to treat differential rates for different levels of income as a structural feature of the tax code but differential rates for different types of income as a tax expenditure.

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Concentrate on the differential in the income yields between bonds and stocks.

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The low corporate tax (and the 1:2.25 differential between it and the income tax) encourages a lot of tax shifting.

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