= 10/56 + 10/140 + 10/260 +...+ 10/1400
= 5/28 + 5/70 + 5/130 + ... + 5/700
= 5/4.7 + 5/7.10 + 5/10.13 + ... + 5/25.28
= 5.1/3.(3/4.7 + 3/7.10 + 3/10.13 + ... + 3/25.28)
= 5/3.(1/4 - 1/7 + 1/7 - 1/10 + 1/10 - 1/13 + ... + 1/25 - 1/28)
= 5/3.(1/4 - 1/28)
= 5/3.3/14
= 5/14
Tính nhanh:
\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Tính:
15 / 90 . 94 + 15 / 94 . 98 + 15 / 98 .102+...+ 15 / 146.150
10 / 56 + 10/ 140 + 10 / 260+...+ 10 /1400
10/56 + 10/140 + 10/260 + ...........+ 10/1400
Ai nhanh nhất và đúng nhất cho 10 tk
Ko thik thì cho 5 tk cũng được :)
Ai sắp thi rồi ko ?
\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)=?
\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
Thank !!!
Tính nhanh : A = 1/8 + 1/56 + 1/140 + 1/260 + 1/416
10/50+10/140+10/260+.....+10/1400
D=\(\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}\)
E=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+.....\frac{10}{1400}\)
71+65*4 =y+140/y+260
