Tìm y ( 1/1×3 + 1/3×5 + 1/5×7 + 1/7×9 + 1/9×11 ) x y= 2/3 Mn giúp em với ạ, em cảm ơn nhiều!

0 bình luận về “Tìm y ( 1/1×3 + 1/3×5 + 1/5×7 + 1/7×9 + 1/9×11 ) x y= 2/3 Mn giúp em với ạ, em cảm ơn nhiều!”

1. Đáp án:

   `y=22/15`

   Giải thích các bước giải:

   `(1/(1xx3)+1/(3xx5)+1/(5xx7) + 1/(7xx9)+1/(9xx11))xxy= 2/3`

   `(1/(1xx3)+1/(3xx5)+1/(5xx7) + 1/(7xx9)+1/(9xx11))xxy= 1/2xx4/3`

   `2xx(1/(1xx3)+1/(3xx5)+1/(5xx7) + 1/(7xx9)+1/(9xx11))xxy= 4/3`

   `(2/(1xx3)+2/(3xx5)+2/(5xx7) + 2/(7xx9)+2/(9xx11))xxy= 4/3`

   `(1 – 1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)xxy=4/3`

   `(1-1/11)xxy=4/3`

   `10/11xxy=4/3`

   `y=4/3 : 10/11`

   `y=4/3xx11/10`

   `y=22/15`

   Trả lời

2. $(\dfrac{1}{1\times3}+\dfrac{1}{3\times5}+\dfrac{1}{5\times7}+\dfrac{1}{7\times9}+\dfrac{1}{9\times11})\times y=\dfrac{2}{3}$

   $2\times(\dfrac{1}{1\times3}+\dfrac{1}{3\times5}+\dfrac{1}{5\times7}+\dfrac{1}{7\times9}+\dfrac{1}{9\times11})\times y=\dfrac{2}{3}\times2$

    $\dfrac{2}{1\times3}+\dfrac{2}{3\times5}+\dfrac{2}{5\times7}+\dfrac{2}{7\times9}+\dfrac{2}{9\times11})\times y=\dfrac{4}{3}$

   $(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11})\times y=\dfrac{4}{3}$

   $(1-\dfrac{1}{11})\times y=\dfrac{4}{3}$

   $\dfrac{10}{11})\times y=\dfrac{4}{3}$

   $y=\dfrac{4}{3}:\dfrac{10}{11}$

   $y=\dfrac{22}{15}$

   Vậy $y=\dfrac{22}{15}$

   Trả lời