2/5+2/45+2/117+2/221=?
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/05 14:15:45
2/5+2/45+2/117+2/221=?
2/5+2/45+2/117+2/221
=(1-1/5)/2+(1/5-1/9)/2+(1/9-1/13)/2+(1/13-1/17)/2
=[(1-1/5)+(1/5-1/9)+(1/9-1/13)+(1/13-1/17)]/2
=(1-1/17)/2
=8/17
再问: 灾情问这位大虾: 33又8/11 * 49又61/62 + 28又3/11 * 159又61/62 =? 乘号用 * 代替 (1+1/3)*(1+1/9)*(1+1/81)=? 1 + 3又1/6 + 5又1/12 + 7又1/20 + 9又1/30 + 11又1/42=? 1 + 1/(1+2) + 1/(1+2+3) + ..... +1/(1+2+3+4+5+6+7+8+9+10)=?
再答: 第一题没看明白 (1+1/3)*(1+1/9)*(1+1/81) =(1-1/3)(1+1/3)*(1+1/9)*(1+1/81)/(1-1/3) 利用平方差公式 =(1-1/81²)*3/2 =(81²-1)/81² *3/2=....... 1 + 3又1/6 + 5又1/12 + 7又1/20 + 9又1/30 + 11又1/42=? =(1+3+5+7+9+11)+(1/6+1/12+1/20+1/30+1/42) =36+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7) =36+1/2-1/7 =36又5/14 1 + 1/(1+2) + 1/(1+2+3) + ..... +1/(1+2+3+4+5+6+7+8+9+10) =1/1+1/3+1/6+1/10+....+1/45 =2(1/2+1/6+1/12+1/20.....+1/90) =2(1-1/2+1/2-1/3+1/3-1/4+....+1/9-1/10) =2*(1-1/10) =9/5
=(1-1/5)/2+(1/5-1/9)/2+(1/9-1/13)/2+(1/13-1/17)/2
=[(1-1/5)+(1/5-1/9)+(1/9-1/13)+(1/13-1/17)]/2
=(1-1/17)/2
=8/17
再问: 灾情问这位大虾: 33又8/11 * 49又61/62 + 28又3/11 * 159又61/62 =? 乘号用 * 代替 (1+1/3)*(1+1/9)*(1+1/81)=? 1 + 3又1/6 + 5又1/12 + 7又1/20 + 9又1/30 + 11又1/42=? 1 + 1/(1+2) + 1/(1+2+3) + ..... +1/(1+2+3+4+5+6+7+8+9+10)=?
再答: 第一题没看明白 (1+1/3)*(1+1/9)*(1+1/81) =(1-1/3)(1+1/3)*(1+1/9)*(1+1/81)/(1-1/3) 利用平方差公式 =(1-1/81²)*3/2 =(81²-1)/81² *3/2=....... 1 + 3又1/6 + 5又1/12 + 7又1/20 + 9又1/30 + 11又1/42=? =(1+3+5+7+9+11)+(1/6+1/12+1/20+1/30+1/42) =36+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7) =36+1/2-1/7 =36又5/14 1 + 1/(1+2) + 1/(1+2+3) + ..... +1/(1+2+3+4+5+6+7+8+9+10) =1/1+1/3+1/6+1/10+....+1/45 =2(1/2+1/6+1/12+1/20.....+1/90) =2(1-1/2+1/2-1/3+1/3-1/4+....+1/9-1/10) =2*(1-1/10) =9/5
sin(45/2)/cos(45/2)=?
1+2+3+4+5+6+7+8+9+10.116+117+118+119=?
45+(x-45)/5=x/2解方程
2/5+2/9+7/45等于?
9√45*1/3√2/5*3/5√2又2/3=?
方程:x+2/5x=45 问:x=?
把5-2代入方程有:(5-2)2+m(5-2)+n=0,9-45
设矩阵A=221,110,-123,求矩阵B,使得A+2B=AB
2/5+5/2=
已知 (1) 标况下 2C(s)+O2(g)==2CO2(g) △H=-221KJ/mol
x=2:2:8;y=[1 2 2 1];subplot(221);plot([x;x],[zeros(1,4);[1 2
14日化学45分钟14页 8.已知①101KPa时,2C(S)+O2(g)=2CO(g) △H=-221KJ/mol;②