1*2+2*3+3*4+4*5+5*6+……48*49+49*50
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:2024/07/08 22:32:31
1*2+2*3+3*4+4*5+5*6+……48*49+49*50
简便计算,十万火急!
简便计算,十万火急!
![1*2+2*3+3*4+4*5+5*6+……48*49+49*50](/uploads/image/z/6427001-65-1.jpg?t=1%2A2%2B2%2A3%2B3%2A4%2B4%2A5%2B5%2A6%2B%E2%80%A6%E2%80%A648%2A49%2B49%2A50)
n(n+1)=n^2+n
1*2+2*3+3*4+4*5+5*6+……n(n+1)
=(1^2+2^2+……+n^2)+(1+2+……+n)
=n(n+1)(2n+1)/6+n(n+1)/2
=n(n+1)(n+2)/3
1*2+2*3+3*4+4*5+5*6+……48*49+49*50
=49*(49+1)*(49+2)/3
=41650
1*2+2*3+3*4+4*5+5*6+……n(n+1)
=(1^2+2^2+……+n^2)+(1+2+……+n)
=n(n+1)(2n+1)/6+n(n+1)/2
=n(n+1)(n+2)/3
1*2+2*3+3*4+4*5+5*6+……48*49+49*50
=49*(49+1)*(49+2)/3
=41650
1*2+2*3+3*4+4*5+5*6+……48*49+49*50
1/2*3+1/3*4+1/4*5……+1/48*49+1/49*50是多少
1*1-2*2+3*3-4*4+5*5-6*6+…+49*49-50*50=
1/1×3+1/3×5+1/5×7+…………+1/49×51和1/2×4+1/4×6+1/6×8+…………1/48×50
5/(2*1)+5/(2*3)+5/(3*4)……5/(49*50)等于多少
1、2、3、4、5、6、7、8、9…………45、46、47、48、49、50,这50个数相乘结果有几个0
巧算:50-49+48-47+…+4-3+2-1
1/2×2/3×3/4×4/5×5/6×.× 47/48×48/49×49/50的算法
1/2×3+1/3×4+1/4×5+……+1/49×50
计算:1+2+3+4+…+48+49+50+49+48+…+4+3+2+1.
1*2+2*3+3*4+…+48*49+49*50
5+8+11+14+…+29+30=?1-2+3-4+5-6+7-…-48+49=?