Question

1乘2加2乘3加3乘4一直加到100乘101的详细求值的过程要说清楚

Answer 1

满意答案1*2+2*3+3*4+.+100*101

=1/3*1*2*3+1/3[2*3*4-1*2*3]+1/3[3*4*5-2*3*4]+.+1/3[100*101*102-99*100*101]

=1/3[1*2*3+2*3*4-1*2*3+3*4*5-2*3*4+.+100*101*102-99*100*101]

=1/3*100*101*102

=343400