请用简便算法解下面这道题,99×99-98×98
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请用简便算法解下面这道题,99×99-98×98
请用简便算法解下面这道题,
99×99-98×98
请用简便算法解下面这道题,99×99-98×98
(99-98)(99+98)=197
(98+1)*(98+1)-98*98
=(98*98+98*1+98*1+1*1)-98*98
=98*2+1
=197
99*99-98*98
=98+99
=197
99*99-98*98=(98+1)*(98+1)-98*98=98*98+2*98+1-98*98=197
99*99-(99-1)*(99-1)
=99*99-{(99*99)-2*【100-1】+1}
=99*99-【99*99-(200-2)+1】
=197
=(100-1)*99-(100-2)*98
=(100*99-1*99)-(100*98-2*98)
=(9900-99)-(9800-196)
=(9900-9800)-99+196
=100-99+196
=197
*为乘
原式=99×99-(99-1)×(99-1)
=99²-(99²-198+1)
=197
197
99×99-98×98
=(98+1)×99-98×(99-1)
=98×99+99-98×99+98
=99+98
=197