7245-7244=7244.(72-1)=7244.71
7244-7243=7243.(72-1)=7243.71
Do 7244.71>7243.71
Nên 7245-7244>7244-7243
đặt A=72^45-72^44=72^44.(72-1) (1)
B=72^44-72^43=72^43.(72-1) (2)
từ 1 và 2 => A>B
72^45-72^44
=72^1.72^44-72^44.1
=71.72^44
72^44-72^43
= 71.72^43
vì:72^44>72^43
nen :72^45-72^44>72^44-72^43