Tính thuận tiện
Ta có :
\(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}\)
= \(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\)
= \(\frac{1}{1}-\frac{1}{11}\)
= \(\frac{10}{11}\)
2/1x3 + 2/3x5 + 2/5x7 + 2/7x9 + 2/9x11
tính bằng cách thuận tiện;2/1x3+2/3x5+2/5x7+2/7x9+2/9x11
tìm y:(1/1x3+1/3x5+1/5x7+1/7x9+1/9x11)xy=2/3
Tìm y biết:
\(\left(\frac{2}{1x3}+\frac{2}{3x5}+\frac{2}{5x7}+\frac{2}{7x9}+\frac{2}{9x11}\right)\cdot y=\frac{2}{3}\)
tìm y ( 1/1x3 + 1/3x5 + 1/5x7 + 1/7x9 + 1/9x11 ) xy = 2/3
nhanh hộ tớ nhé chiều nay tớ phải nộp
1/1x3+1/3x5+1/5x7+1/7x9=1/9x11
1/1x3+1/3x5+1/5x7+1/7x9+1/9x11 = ?
2/3x5 + 2/5x7 + 2/7x9 + 2/9x11 + 2/11x13
(1/1x3+1/3x5+1/5x7+1/7x9+1/9x11+1/11x13)xy=3/5
4/1x3 - 8/3x5 + 12/5x7 -16/7x9 + 20/9x11 - 24/11x13
giúp mình giải bài nay với ạ
