奥数(1+569+798)*(655+500+345)-(1+655+500+345)*(569+798)=

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奥数(1+569+798)*(655+500+345)-(1+655+500+345)*(569+798)=

奥数(1+569+798)*(655+500+345)-(1+655+500+345)*(569+798)=
奥数(1+569+798)*(655+500+345)-(1+655+500+345)*(569+798)=

奥数(1+569+798)*(655+500+345)-(1+655+500+345)*(569+798)=
用换元法
令(569+798)=a
(1+569+798)=a+1
(655+500+345)=b
(1+655+500+345)=b+1
原式=(a+1)×b-(b+1)×a
=ab+b-ab-a
=b-a
=655+500+345-569-798=133

计算器!!

(1+569+798)*(655+500+345)-(1+655+500+345)*(569+798)
=(1+569+798)*1500-(1500+1)*(569+798)
=1500+569*1500+798*1500-1500*569-569-1500*798-798
=1500-569-798
=1500-600-800+31+2
=133 .