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1, limit four operations, arbitrary compound operations, as long as the operations between formulas are established;
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2. The mistake is not that the four operations cannot be used, but that it is wrong.
The substitution method that can only be applied to shape determination and the calculation of infinitives is just one of them;
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The second is the overuse and abuse of equivalent infinitesimal substitution which can only be used in China.
Because the so-called equivalent infinitesimal substitution is to steal the expansion of McLaughlin series and Taylor series
After the first item, the sham as the genuine, deceives people, because there is no theory of its own, no.
Self-consistent system, indiscriminate use of equivalent infinitesimal substitution method, is bound to make mistakes often. Therefore,
The equivalent infinitesimal replacement method sets the rules of self-mutilation, self-abuse and having a guilty conscience:
When there is addition and subtraction, you can't replace it with equivalent infinitesimal, which is ridiculous!
When there are addition and subtraction operations, the equivalent infinitesimal substitution method can sometimes be used, and sometimes it can't be used!
Because equal-order infinitesimal substitution is a way of stealing chickens and dogs, and it is not bad.
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Speaking of which, maybe the landlord was shocked.
For example, it is easy to understand.
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When x tends to 0, (tanx-sinx)/x? Tanx ~ x； on the molecule; sinx ~ x；
A far-fetched and willful teacher will tell us that when adding and subtracting, the order is infinitesimal.
The replacement method cannot be used; Addition and subtraction, four operations, will make mistakes; 、、、、、、
In fact, as long as it is expanded by McLaughlin series, this limit will not go wrong at all!
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Does the landlord understand the above two reasons?
If you have any questions, please ask them. If you have any questions, you will have answers.
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