tìm y:(1/1x3+1/3x5+1/5x7+1/7x9+1/9x11)xy=2/3
(1/1x3+1/3x5+1/5x7+1/7x9+1/9x11+1/11x13)xy=3/5
1/1x3+1/3x5+1/5x7+1/7x9=1/9x11
1/1x3+1/3x5+1/5x7+1/7x9+1/9x11 = ?
\(\left(\frac{1}{1x3}+\frac{1}{3x5}+\frac{1}{5x7}+\frac{1}{7x9}+\frac{1}{9x11}\right)\)
Tính
\(\frac{1}{1x3}+\frac{1}{3x5}+\frac{1}{5x7}+\frac{1}{7x9}+\frac{1}{9x11}\)
A = 2/1x3 + 2/3x5 + 2/5x7 +...+ 2/ 21x23
B=1/6 + 1/12 +1/20 +1/30+1/42+1/56+1/72+1/90
C=1/28+1/70 +1/130+1/208
mng ơi giúp tớ vs aa tớ đg cần rất gấp, tớ cảm ơn mng trước ạ!!!
hnay tớ phải nộp rùi , giúp tớ vs aa=(
2/1x3 + 2/3x5 + 2/5x7 + 2/7x9 + 2/9x11
4/1x3 - 8/3x5 + 12/5x7 -16/7x9 + 20/9x11 - 24/11x13
giúp mình giải bài nay với ạ