新版GRE数学复习重要考点:Substitution

所属专题:GRE数学重要考点  来源:互联网    要点:GRE考试  
编辑点评: 新GRE数学考试的难度有所增加,但是只要大家认真准备,掌握了基本的知识,还是可以在原有的水平上考出出色的分数的。本文为大家整理汇总了新GRE数学考试的复习要点,希望对大家的复习有所帮助。

本文为大家介绍的GRE数学复习考点是“代入法”。

新版GRE数学复习重要考点:Substitution

Substitution is a method where one or more variables in an expression is replaced by numbers or another set of variables.To evaluate an expression specific numbers are used as substitute. To express in terms of another set of variables, variables are replaced by the new set of variables.

Example:

If x=3, then 2x2+4x+1 can be evaluated by substituting 3 for x.

Replacing all x by 3, we get 2*32+4*3+1=31.

If x=2+y, then x2-3 can be expressed in terms of y by replacing all x by (2+y):(2+y)2-3=y2+4y+1.

Remember:

Do not forget to replace all occurrences of the variable.

After substitution the variable does not appear anywhere in the expression.

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