新GRE數學複習要點之Substitution

Substitution

Substitution is a method where one or more variables in an expression is replaced by numbers or another set of 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.

由於美國數學基礎教育的難度增加導致數學考試越來越難，但新gre數學複習考點都是高中時候學到的知識點，考生不要過於緊張，把基本概念弄明白，再記住一些新版gre數學必備的詞彙，那麼相信新版gre數學應該沒有問題。