Tìm x:
\(\frac{x-1}{99}\)+\(\frac{x-2}{98}+\frac{x-5}{95}=3+\frac{1}{99}+\frac{1}{98}+\frac{1}{95}\)
(1 – 2 + 3 – 4 + 5 – 6 + 7 – 8 +........– 98 + 99) x (2013 x 6 – 2013 – 2013 x 5)
Tnh tổng sau bằng cách hợp lí:
S = 1 x 2 x 3 + 2 x 3 x 4 + 3x 4 x 5 + 4 x 5 x 6 + … + 97 x 98 x 99
x : 3 + 1 - 2 + 3 - 4 + 5 - 6 + ...... + 97 - 98 + 99 = 127
X|3+1-2+3-4+5-6+...+97-98+99=127
tim x
x : 3 + 1 - 2 + 3 - 4 + 5 - 6 + .......... + 97 - 98 + 99 = 127
Find x , if
x : 3 + 1 - 2 + 3 - 4 + 5 - 6 + ... + 97 - 98 + 99 = 127
tính nhanh (2/3+3/4+5/6+...+99/100).(1/2+2/3+3/4+...+98/99)-(1/2+1/3+...+99/100).(2/3+2/4+...+98/99)
\(\frac{101+100+99+98+.....+5+4+3+2+1}{101-100+99-98+...+5-4+3-2+1}\)