Question

Đã trả lời bởi chuyên gia

Answer 1

\[\begin{array}{l}
\left( {{\rm{ }}y{\rm{ }} - {\rm{ }}1/6{\rm{ }}} \right){\rm{ }} + {\rm{ }}\left( {{\rm{ }}y{\rm{ }} - {\rm{ }}1/12{\rm{ }}} \right){\rm{ }} + {\rm{ }}.{\rm{ }}.{\rm{ }}.{\rm{ }} + {\rm{ }}\left( {{\rm{ }}y{\rm{ }} - {\rm{ }}1/90{\rm{ }}} \right){\rm{ }} = {\rm{ }}3/5\;\\
y - \frac{1}{6} + y - \frac{1}{{12}} + ... + y - \frac{1}{{90}} = \frac{3}{5}\\
y \times 8 - \frac{1}{{2 \times 3}} - \frac{1}{{3 \times 4}} - ... - \frac{1}{{9 \times 10}} = \frac{3}{5}\\
y \times 8 - (\frac{1}{2} - \frac{1}{3} + \frac{1}{3} - \frac{1}{4} + ... + \frac{1}{9} - \frac{1}{{10}}) = \frac{3}{5}\\
y \times 8 - (\frac{1}{2} - \frac{1}{{10}}) = \frac{3}{5}\\
y \times 8 - \frac{2}{5} = \frac{3}{5}\\
y \times 8 = \frac{3}{5} + \frac{2}{5} = 1\\
y = 1:8\\
y = \frac{1}{8}
\end{array}\]

Answer 2

HD:

$(y - \frac{1}{2.3}) + (y - \frac{1}{3.4}) + . . . + (y - \frac{1}{9.10}) = \frac{3}{5} \Rightarrow 8 y - (\frac{1}{2.3} + \frac{1}{3.4} + . . . + \frac{1}{9.10}) = \frac{3}{5} (ở đ â y l à 8 y d o t ừ 2 - 9 c ó 8 s ố, t ứ c l à 8 l ầ n y c ộ n g v ớ i n h a u) \Rightarrow 8 y - (\frac{3 - 2}{2.3} + \frac{4 - 3}{3.4} + . . . + \frac{10 - 9}{9.10}) = \frac{3}{5} \Rightarrow 8 y - (\frac{1}{2} - \frac{1}{3} + \frac{1}{3} - \frac{1}{4} + . . . + \frac{1}{9} - \frac{1}{10}) = \frac{3}{5} \Rightarrow 8 y - (\frac{1}{2} - \frac{1}{10}) = \frac{3}{5} \Rightarrow 8 y - \frac{5 - 1}{10} = \frac{3}{5} \Rightarrow 8 y - \frac{2}{5} = \frac{3}{5} \Rightarrow 8 y = \frac{2}{5} + \frac{3}{5} = 1 \Rightarrow 8 y = 1 \Rightarrow y = 1 / 8 V ậ y y = 1 / 8$

...Xem thêm

Answer 3

HD:

$(y - \frac{1}{2.3}) + (y - \frac{1}{3.4}) + . . . + (y - \frac{1}{9.10}) = \frac{3}{5} \Rightarrow 8 y - (\frac{1}{2.3} + \frac{1}{3.4} + . . . + \frac{1}{9.10}) = \frac{3}{5} (ở đ â y l à 8 y d o t ừ 2 - 9 c ó 8 s ố, t ứ c l à 8 l ầ n y c ộ n g v ớ i n h a u) \Rightarrow 8 y - (\frac{3 - 2}{2.3} + \frac{4 - 3}{3.4} + . . . + \frac{10 - 9}{9.10}) = \frac{3}{5} \Rightarrow 8 y - (\frac{1}{2} - \frac{1}{3} + \frac{1}{3} - \frac{1}{4} + . . . + \frac{1}{9} - \frac{1}{10}) = \frac{3}{5} \Rightarrow 8 y - (\frac{1}{2} - \frac{1}{10}) = \frac{3}{5} \Rightarrow 8 y - \frac{5 - 1}{10} = \frac{3}{5} \Rightarrow 8 y - \frac{2}{5} = \frac{3}{5} \Rightarrow 8 y = \frac{2}{5} + \frac{3}{5} = 1 \Rightarrow 8 y = 1 \Rightarrow y = 1 / 8 V ậ y y = 1 / 8$

3 câu trả lời 374

Câu hỏi hot cùng chủ đề

Bài viết mới nhất Lớp 5