Question

\(A=\frac{55}{11X16}+\frac{55}{16X21}+\frac{55}{21X26}+\frac{55}{26X31}+\frac{55}{31X36}+\frac{55}{36X41}\)

Answer 1

\(A=\frac{55}{11.16}+\frac{55}{16.21}+\frac{55}{21.26}+......+\frac{55}{36.41}\)

\(=11\left(\frac{5}{11.16}+\frac{5}{16.21}+......+\frac{5}{36.41}\right)\)

\(=11.\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+.......+\frac{1}{36}-\frac{1}{41}\right)\)

\(=11.\left(\frac{1}{11}-\frac{1}{41}\right)\)

\(=11.\frac{30}{451}=\frac{30}{41}\)

Answer 2

toán 5 | Diễn đàn HOCMAI - Cộng đồng học tập lớn nhất Việt Nam

Answer 3

\(A=\frac{55}{11X16}+\frac{55}{16X21}+\frac{55}{21X26}+\frac{55}{26X31}+\frac{55}{31X36}+\frac{55}{36X41}\)

\(A=11X\left(\frac{5}{11X16}+\frac{5}{16X21}+\frac{5}{21X26}+\frac{5}{26X31}+\frac{5}{31X36}+\frac{5}{36X41}\right)\)

\(A=11X\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+\frac{1}{26}-\frac{1}{31}+\frac{1}{31}-\frac{1}{36}+\frac{1}{36}-\frac{1}{41}\right)\)

\(A=11X\left(\frac{1}{11}-\frac{1}{41}\right)\)

\(A=11X\frac{1}{11}-11X\frac{1}{41}\)

\(A=1-\frac{11}{41}\)

\(A=\frac{30}{41}\)

Answer 4

Bạn vào đây tham khảo:

toán 5/tth/Diễn đàn HOCMAI 

Mình thấy giống bài của bạn đó!

^_^

Answer 5

\(\frac{A}{11}=\frac{5}{11.16}+\frac{5}{16.21}+....+\frac{5}{36.41}\)

\(\frac{A}{11}=\frac{16-11}{11.16}+\frac{21-16}{16.21}+....+\frac{41-36}{36.41}\)

\(\frac{A}{11}=\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+....+\frac{1}{36}-\frac{1}{41}\)

\(\frac{A}{11}=\frac{1}{11}-\frac{1}{41}=\frac{30}{11.41}\)

Suy Ra \(A=\frac{11.30}{11.41}=\frac{30}{41}\)

Answer 6

A=11 X ( \(\frac{5}{11x16}\)+ \(\frac{5}{16x21}\)+ \(\frac{5}{21x26}\)+ ...+ \(\frac{5}{36x41}\))

A= 11 X ( \(\frac{16-11}{11X16}\)+ \(\frac{21-16}{16X21}\)+ \(\frac{26-21}{21X26}\)+...+ \(\frac{41-36}{36X41}\))

A= 11 X ( \(\frac{16}{11X16}\) \(-\frac{11}{11X16}\)+ \(\frac{21}{16X21}\)\(-\frac{16}{16X21}\)+...+ \(\frac{41}{36X41}\)\(-\frac{36}{36X41}\) )

A= 11 X ( \(\frac{1}{11}\)\(-\frac{1}{16}\)+\(\frac{1}{16}\)\(-\frac{1}{21}\)\(+\)... \(+\frac{1}{36}\)\(-\frac{1}{41}\))

A= 11 X ( \(\frac{1}{11}-\frac{1}{41}\))

A= 11 X \(\frac{30}{11X41}\)

A= \(\frac{11X30}{11X41}\)

A= \(\frac{30}{41}\).

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Answer 7

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https://olm.vn/hoi-dap/detail/6781059325.html

Cbht 

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