`-(1)/(99)-(1)/(99.98)-(1)/(98.97)-(1)/(97.96)-...-(1)/(3.2)-(1)/(2.1)`
`=-(1)/(99)-((1)/(1.2)+(1)/(2.3)+...+(1)/(96.97)+(1)/(97.98)+(1)/(98.99))`
`=-(1)/(99)-(1-(1)/(2)+(1)/(2)-(1)/(3)+...+(1)/(96)-(1)/(97)+(1)/(97)-(1)/(98)+(1)/(98)-(1)/(99))`
`=-(1)/(99)-(1-(1)/(99))`
`=-(1)/(99)-1+(1)/(99)`
`=-1`
Chao. giai cho vui thoi nhe
A= 1 - 1 - 1 - 1 - 1 - ... - 1
100x99 99x98 98x97 97x96 96x95 2x1
A=?
1/2x1+1/3x(1+2)+1/4x(1+2+3)+...+1/100x(1+2+3+...+99+100)
Giup minh voi
1/1x1/2+1/2x1/3+1/3x1/4+...+1/79x1/80
1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7+1/7x1/8+1/8x1/9
Tính nhanh 5/2x1 + 4/1x11 + 3/11x12 + 1/2x15 + 1/2x15 + 13/15x4
(1+97)*(1+97/2)*(1+97/3)*(1+97/4)... ... ...(1+97/99)
(1+99)*(1+99/2)*(1+99/3)*(1+99/4)... ... ...(1+99/97)
5/(2x1) + 4/(1x11) + 3/(11x2) + 1/(2x15) + 13/(15x4) = ?
Ko quy đồng mẫu các phân số, hãy tính hợp lý tổng sau:
B= 5/2x1 + 1/1x11 + 3/11x2 + 1/2x15 + 13/15x4
tinh : B=5/2x1 +4/1x11 + 3/11x2 +2/11x2 + 1/2x15 + 13/15x4
tinh tong gia tri bieu thuc :
a)A=1+1/3+1/5+...+1/97+1/99/1/1*99+1/3*97+1/5*95+...+1/97*3+1/99*1
b)B=1/2+1/3+1/4+...+1/100/99/1+98/2+97/3+...+1/99
