\(\frac{1}{1.3}+\frac{1}{3.5}+....+\frac{1}{9.11}=\frac{1}{2}\left(\frac{2}{1.3}+\frac{1}{3.5}+....+\frac{2}{9.11}\right)\)
\(=\frac{1}{2}\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-....-\frac{1}{11}\right)=\frac{1}{2}.\left(1-\frac{1}{11}\right)\)
\(=\frac{1}{2}.\frac{10}{11}=\frac{5}{11}\)
1/1x3+1/3x5+1/5x7+1/7x9=1/9x11
(1/1x3+1/3x5+1/5x7+1/7x9+1/9x11+1/11x13)xy=3/5
tìm y:(1/1x3+1/3x5+1/5x7+1/7x9+1/9x11)xy=2/3
\(\left(\frac{1}{1x3}+\frac{1}{3x5}+\frac{1}{5x7}+\frac{1}{7x9}+\frac{1}{9x11}\right)\)
tìm y ( 1/1x3 + 1/3x5 + 1/5x7 + 1/7x9 + 1/9x11 ) xy = 2/3
nhanh hộ tớ nhé chiều nay tớ phải nộp
Tính
\(\frac{1}{1x3}+\frac{1}{3x5}+\frac{1}{5x7}+\frac{1}{7x9}+\frac{1}{9x11}\)
2/1x3 + 2/3x5 + 2/5x7 + 2/7x9 + 2/9x11
1/3x5+1/5x7+1/7x9+1/9x11+1/11x13
1/1x3 + 1/3x5 + 1/5x7 + 1/7x9
