(2/11*13+2/13*15+2/15*17+2/17*19+2/19*21)*462-x=19 tìm x 24/08/2021 Bởi Faith (2/11*13+2/13*15+2/15*17+2/17*19+2/19*21)*462-x=19 tìm x
Đáp án:x=1 Giải thích các bước giải: (2/11*13+2/13*15+2/15*17+2/17*19+2/19*21)*462-x=19 -> (1/11-1/13+1/13-1/15+1/15-1/17+1/17-1/19+1/19-1/21)*462-x=19 -> (1/11-1/21)*462-x=19 -> 10/231*462-x=19 -> 20-x=19 -> x=20-19 -> x=1 Bình luận
Đáp án: \(x=1\) Giải thích các bước giải: \[\begin{array}{l}\left( {\frac{2}{{11 \times 13}} + \frac{2}{{13 \times 15}} + \frac{2}{{15 \times 17}} + \frac{2}{{17 \times 19}} + \frac{2}{{19 \times 21}}} \right) \times 462 – x = 19\\\left( {\frac{1}{{11}} – \frac{1}{{13}} + \frac{1}{{13}} – \frac{1}{{15}} + \frac{1}{{15}} – \frac{1}{{17}} + \frac{1}{{17}} – \frac{1}{{19}} + \frac{1}{{19}} – \frac{1}{{21}}} \right) \times 462 – x = 19\\\left( {\frac{1}{{11}} – \frac{1}{{21}}} \right) \times 462 – x = 19\\\frac{{10}}{{231}} \times 462 – x = 19\\20 – x = 19\\x = 20 – 19\\x = 1\end{array}\] Bình luận
Đáp án:x=1
Giải thích các bước giải:
(2/11*13+2/13*15+2/15*17+2/17*19+2/19*21)*462-x=19
-> (1/11-1/13+1/13-1/15+1/15-1/17+1/17-1/19+1/19-1/21)*462-x=19
-> (1/11-1/21)*462-x=19
-> 10/231*462-x=19
-> 20-x=19
-> x=20-19
-> x=1
Đáp án:
\(x=1\)
Giải thích các bước giải:
\[\begin{array}{l}
\left( {\frac{2}{{11 \times 13}} + \frac{2}{{13 \times 15}} + \frac{2}{{15 \times 17}} + \frac{2}{{17 \times 19}} + \frac{2}{{19 \times 21}}} \right) \times 462 – x = 19\\
\left( {\frac{1}{{11}} – \frac{1}{{13}} + \frac{1}{{13}} – \frac{1}{{15}} + \frac{1}{{15}} – \frac{1}{{17}} + \frac{1}{{17}} – \frac{1}{{19}} + \frac{1}{{19}} – \frac{1}{{21}}} \right) \times 462 – x = 19\\
\left( {\frac{1}{{11}} – \frac{1}{{21}}} \right) \times 462 – x = 19\\
\frac{{10}}{{231}} \times 462 – x = 19\\
20 – x = 19\\
x = 20 – 19\\
x = 1
\end{array}\]