1*2+2*3+3*4+……+50*51
来源:学生作业帮 编辑:大师作文网作业帮 分类:数学作业 时间:2024/10/03 10:37:48
1*2+2*3+3*4+……+50*51
设n=1*2+2*3+3*4+……+50*51
则2n = 1*2+2*3+3*4+……+50*51
+1*2+2*3+3*4+……+50*51
=1*2+2*4+3*6+4*8+……+50*100+50*51
=2(1^2+2^2+3^2+4^2+……+50^2)+50*51
根据公式1^2+2^2+……+n^2=[(n+1)(2n+1)n]/6
则得:1^2+2^2+3^2+4^2+……+50^2=[(50+1)(2*50+1)*50]/6
=(51*101*50)/6
=(51/3)*(50/2)*101
=42925
得:2n = 2*42925+50*51=85850+2550=88400
得:n=88400/2=44200
则2n = 1*2+2*3+3*4+……+50*51
+1*2+2*3+3*4+……+50*51
=1*2+2*4+3*6+4*8+……+50*100+50*51
=2(1^2+2^2+3^2+4^2+……+50^2)+50*51
根据公式1^2+2^2+……+n^2=[(n+1)(2n+1)n]/6
则得:1^2+2^2+3^2+4^2+……+50^2=[(50+1)(2*50+1)*50]/6
=(51*101*50)/6
=(51/3)*(50/2)*101
=42925
得:2n = 2*42925+50*51=85850+2550=88400
得:n=88400/2=44200
1*2+2*3+3*4+……+50*51
2-1+3-2+4-3+……+50-49+51-50
原式=1+3+5……+101-(2+4+6+……100) =(1+101)*51/2-(2+100)*50/2 =51
(1×2/1)+1+(2×3/1)+2+(3×4/1)+3+……+(50×51/1)+50要讲解的!
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
求1/2+(3/1+2/3)+(1/4+2/4+3/4)+……+(1/50+2/50+3/50+……+48/50+49/
100^3+99^3/100^3+1^+99^3+97^3/99^3+2^3……+51^3+1^/51^3+50^3=?
奥数题1+2+3+4+……+49+50
1*2*3*4*5*6*……*50=
计算:1+3+5+7+9+……+51和2+4+6+8+10+……+60
①1+2+3+….…+1999 ②2000-3-6-9-……-51
1/2×3+1/3×4+1/4×5+……+1/49×50