(99²+98²+…+90²)-(89²+88²+…+80²
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/08/08 18:43:43
(99²+98²+…+90²)-(89²+88²+…+80²)
![(99²+98²+…+90²)-(89²+88²+…+80²](/uploads/image/z/5607120-48-0.jpg?t=%2899%26sup2%3B%2B98%26sup2%3B%2B%E2%80%A6%2B90%26sup2%3B%29-%2889%26sup2%3B%2B88%26sup2%3B%2B%E2%80%A6%2B80%26sup2%3B)
=(99²-89²)+(98²-88²)+……+(90²-80²)
=(99+89)(99-89)+(98+88)(98-88)+……+(90+80)(90-80)
=(99+89)*10+(98+88)*10+……+(90+80)*10
=(80+81+82+……+99)*10
=(80+99)*20/2*10
=17900
=(99+89)(99-89)+(98+88)(98-88)+……+(90+80)(90-80)
=(99+89)*10+(98+88)*10+……+(90+80)*10
=(80+81+82+……+99)*10
=(80+99)*20/2*10
=17900
(99²+98²+…+90²)-(89²+88²+…+80²
(99²+98²+97²+···90²)-(89²+88²+
100²-99²+98²-97²+96²+……+2²-1&s
计算:100²-99²+98²-97²+……+4²-3²+2
(100²+98²+96²……+2²)-(99²+97²+9
计算:100²-99²+98²-97²+…4²-3²+2&s
100²-99²+98²-97²+…+2²-1
运用这个规律计算:100²-99²+98²-97²+…+54²-53&
100²-99²-98²-97²-.-1²
乘法公式计算100²-99²+98²-97²+……+2²-1²
100²-99²+98²-97²+.4²-3²+2²
1²-2²+3²-4²+5²-6²+…-100²+