T=1/2+1/6+1/12+1/20+1/30+...+1/72+1/90
=> T=1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+...+1/9.10
=> T=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+...+1/9-1/10
=> T=1/1-1/10
=> T=9/10
Cho T = 1/2+1/6+1/12+1/20+1/30+.....+1/72+1/90. Tính T
Cho T = 1/2 + 1/6 + 1/12 + 1/20 + 1/30 +....+1/72 + 1/90
tính bằng cách thuận tiện:1/2+ 1/6+ 1/12+ 1/20 +1/30+ 1/42+ 1/56 +1/72+ 1/90
tính nhanh:
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
Tính bằng cách thuận tiện nhất :1/12+1/20+1/30+...+1/72+1/90
Tính nhanh: A. 1/2 +1/4+1/8+1/16+1/32+1/64+1/128. B. 1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90 + 1/110 Các bạn giúp mình với mình cảm ơn
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}.\)
tính T = 1/2 +1/6+1/12+1/20+1/30+...+1/9702+1/9900
T=
(1/2+1/6+1/12+...+1/72+1/90) : x = 9/20