Question

如果對(duì)于任意非零有理數(shù)a，b定義運(yùn)算*如下：a*b=

a+b

ab

，則2*（3*4）=

 

．

Answer 1

分析：根據(jù)題中所給出的新運(yùn)算法則，把對(duì)應(yīng)的數(shù)值代入對(duì)應(yīng)的式子計(jì)算即可．注意：先算出小括號(hào)內(nèi)的數(shù)值后再計(jì)算括號(hào)外的數(shù)．

解答：解：根據(jù)題意可知
2*（3*4）=2*

3+4

3×4

=2*

7

12

=

2+ 7 12

2× 7 12

=

31

14

．

點(diǎn)評(píng)：對(duì)于新定義運(yùn)算的題型關(guān)鍵是要準(zhǔn)確的找到運(yùn)算符號(hào)對(duì)應(yīng)的代數(shù)式，準(zhǔn)確的把數(shù)值代入對(duì)應(yīng)的位置．對(duì)于有小括號(hào)的代數(shù)式一定要根據(jù)運(yùn)算順序先算小括號(hào)內(nèi)的數(shù)．