Question

比較兩個數(shù)的大小
A=5.4321×1.2345，B=5.4322×1.2344．A

＞

B．

Answer 1

分析：結(jié)合乘法分配律，原式可化為：A=5.4321×1.2345=5.4321×（1.2344+0.0001）=5.4321×1.2344+5.4321×0.0001；B=5.4322×1.2344=（5.4321+0.0001）×1.2344=5.4321×1.2344+1.2344×0.0001，由此可以比較大小．

解答：解：A=5.4321×1.2345=5.4321×（1.2344+0.0001）=5.4321×1.2344+5.4321×0.0001，
B=5.4322×1.2344=（5.4321+0.0001）×1.2344=5.4321×1.2344+1.2344×0.0001，
因?yàn)?.4321×0.0001＞1.2344×0.0001，
所以5.4321×1.2344+5.4321×0.0001＞5.4321×1.2344+1.2344×0.0001，
即A＞B
故答案為：＞．

點(diǎn)評：此類比較大小的題目關(guān)鍵是想法把式子中的因數(shù)化為相同的數(shù)，要運(yùn)用拆數(shù)的技巧并結(jié)合乘法分配律靈活進(jìn)行．