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

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

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

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

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

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

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

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

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

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

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

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

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

\(A=11\left(\frac{5}{11.6}+\frac{5}{16.21}+......+\frac{5}{36.41}\right)\)

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

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

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

Ta có:

55/11x16+55/16x21+55/21x26x.....x55/36x41

=55/5 x (1/11-1/16+1/16-1/21+.......+1/36-1/41)

=55/5 x (1/11-1/41)

=55/5x30/451

=30/41

nhớ ****

\(\frac{A}{11}=\frac{5}{11.16}+\frac{5}{16.21}+\frac{5}{21.26}+\frac{5}{26.31}+\frac{5}{31.36}+\frac{5}{36.41}\)

\(\frac{A}{11}=\frac{16-11}{11.16}+\frac{21-16}{16.21}+\frac{26-21}{21.26}+...+\frac{41-36}{36.41}\)

\(\frac{A}{11}=\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+...+\frac{1}{36}-\frac{1}{41}\)

\(\frac{A}{11}=\frac{1}{11}-\frac{1}{41}=\frac{30}{11.41}\Rightarrow A=\frac{11.30}{11.41}=\frac{30}{41}\)

\(\sqrt[1]{\dfrac{2}{3}_3\dfrac{1}{2}3_3\dfrac{3}{4}^3}\)

`A = 55/( 11xx16 ) + 55/( 16xx21 ) + 55/( 21xx26 ) + 55/( 26xx31) + 55/( 31xx36)+55/(36xx41)`

`A = 11 xx ( 5/( 11xx16 ) + 5/( 16xx21 ) + 5/( 21xx26 ) + 5/( 26xx31) + 5/( 31xx36)+5/(36xx41)`

`A = 11 xx ( 1/11 - 1/16 + 1/16 - 1/21 + 1/21 - 1/26 + 1/26 - 1/31 + 1/31 - 1/36 + 1/36 - 1/41 )`

`A = 11 xx ( 1/11 - 1/41 )`

`A = 1 - 11/41`

`A = 30/41` 

\(A=55.\left(\dfrac{1}{11}-\dfrac{1}{16}+\dfrac{1}{16}-\dfrac{1}{21}+\dfrac{1}{21}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{31}+\dfrac{1}{31}-\dfrac{1}{36}+\dfrac{1}{36}-\dfrac{1}{41}\right)\)

\(A=55\times\left(\dfrac{1}{11}-\dfrac{1}{41}\right)=55\times\dfrac{30}{451}=\dfrac{150}{41}\)

30/41 bạn ạ

150/41 nha

\(\frac{55}{11\times6}+\frac{55}{16\times21}+\frac{55}{21\times26}+..+\frac{55}{36\times41}\)

\(=\frac{11-6}{11\times6}+\frac{21-16}{16\times21}+..+\frac{41-36}{36\times41}\)

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

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

\(=\frac{40}{41}\)

40/41

\(A=\frac{55}{11x16}+\frac{55}{16x21}+\frac{55}{21x26}+\frac{55}{26x31}+\frac{55}{31x36}+\frac{55}{36x41}\)

\(A=11\left(\frac{5}{11x16}+\frac{5}{16x21}+\frac{5}{21x26}+\frac{5}{26x31}+\frac{5}{31x36}+\frac{5}{36x41}\right)\)

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

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

Cảm ơn Trà My nhìu nha ^-^

Bài 1 :

A=.........

A=\(11\left(\frac{5}{11\times16}+\frac{5}{16\times21}+...+\frac{5}{36\times41}\right)\)\(+1\frac{11}{41}\)

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

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

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

A=2

Bài 2 :

Đầu con cá nặng là:

\(150+150\times\frac{1}{2}=225\left(g\right)\)

Thân con cá nặng là:

150+225=375 (g)

Vậy con cá nặng là :

150+225+375=750 (g)

Bài 1: \(A=\frac{55}{11\times16}+\frac{55}{16\times21}+...+\frac{55}{36\times41}+1\frac{11}{41}\)

           \(A=\frac{55}{11\times16}+\frac{55}{16\times21}+...+\frac{55}{36\times41}+\frac{52}{41}\)

           \(A=11\times\left(\frac{5}{11\times16}+...+\frac{5}{36\times41}\right)+\frac{52}{41}\)

           \(A=11\times\left(\frac{1}{11}-\frac{1}{16}+...+\frac{1}{36}-\frac{1}{41}\right)+\frac{52}{41}\)

           \(A=11\times\left(\frac{1}{11}-\frac{1}{41}\right)+\frac{52}{41}\) 

           \(A=11\times\left(\frac{41}{451}-\frac{11}{451}\right)+\frac{52}{41}\)

          \(A=11\times\frac{30}{451}+\frac{52}{41}=\frac{30}{41}+\frac{52}{41}=\frac{82}{41}=2\)

Bài 2: Ta thấy: Đầu = Đuôi + \(\frac{1}{2}\)Thân

                        Thân = Đuôi + Đầu

=> Thân = Đuôi + (Đuôi + \(\frac{1}{2}\)Thân) = 2 x Đuôi + \(\frac{1}{2}\)Thân

=> \(\frac{1}{2}\)Thân = 2 x Đuôi = 2 x 150 = 300 (g)

Thân nặng số g là:     300 x 2 = 600 (g)

Đầu nặng số g là:     600 - 150 = 450 (g)

Cân nặng của con cá là:     600 + 450 + 150 = 1200 (g)

            Đáp số: 1200 g