So sánh hai phân số sau A=11^89+1/11^90+1 và 10^87+1/ 10^88+1
Giải thích
Ta có:
A<1⇒1189+11190+1<1010⇒1189+11190+1<1189+1+101190+1+10=1188+11189+1
1188+11189+1<1⇒1188+11189+1<1010⇒1188+11189+1<1188+1+101189+1+10=1187+11188+1
Vậy A<1188+11189+1<B
Ta có:
A<1⇒1189+11190+1<1010⇒1189+11190+1<1189+1+101190+1+10=1188+11189+1
1188+11189+1<1⇒1188+11189+1<1010⇒1188+11189+1<1188+1+101189+1+10=1187+11188+1
Vậy A<1188+11189+1<B