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\(A=\frac{55}{11.16}+\frac{55}{16.21}+\frac{55}{21.26}+......+\frac{55}{36.41}\)
\(=11\left(\frac{5}{11.16}+\frac{5}{16.21}+......+\frac{5}{36.41}\right)\)
\(=11.\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+.......+\frac{1}{36}-\frac{1}{41}\right)\)
\(=11.\left(\frac{1}{11}-\frac{1}{41}\right)\)
\(=11.\frac{30}{451}=\frac{30}{41}\)
\(\frac{55}{16.21}\)chứ nhỉ.
A=\(\frac{55}{11.16}+\frac{55}{16.21}+\frac{55}{21.26}+\frac{55}{26.31}+\frac{55}{31.36}+\frac{55}{36.41}\)
A= 11.\(\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+....+\frac{1}{36}-\frac{1}{41}\right)\)
A= 11\(\left(\frac{1}{11}-\frac{1}{41}\right)\)
A= 11.\(\frac{30}{451}\)
A= \(\frac{30}{41}\)
\(A=11\left(\frac{5}{11.6}+\frac{5}{16.21}+......+\frac{5}{36.41}\right)\)
\(=11\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+.....+\frac{1}{36}-\frac{1}{41}\right)\)
\(=11\left(\frac{1}{11}-\frac{1}{41}\right)\)
\(=11.\frac{30}{451}=\frac{30}{41}\)
\(M=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\)
\(\Rightarrow M=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{99}-\frac{1}{100}\)
\(\Rightarrow M=1-\frac{1}{100}\)
\(\Rightarrow M=\frac{100}{100}-\frac{1}{100}=\frac{99}{100}\)
\(b,N=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{97.99}\)
\(\Rightarrow N=\frac{1}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}\right)\)
\(\Rightarrow N=\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+..+\frac{1}{97}-\frac{1}{99}\right)\)
\(\Rightarrow N=\frac{1}{2}.\left(1-\frac{1}{99}\right)=\frac{1}{2}.\frac{98}{99}\)
\(\Rightarrow N=\frac{1.98}{2.99}=\frac{49.2}{2.99}=\frac{49}{99}\)
\(a,M=1-\frac{1}{100}=\frac{99}{100}\)
\(b=2N=\frac{2}{1x3}+\frac{2}{3x5}+\frac{2}{5x7}+...+\frac{2}{97x99}\)
\(=1-\frac{1}{99}=\frac{98}{99}\)
=>\(N=\frac{98}{99}:2=\frac{49}{99}\)
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
\(\frac{55}{22}+\frac{44}{22}\)
\(=\frac{55+44}{22}\)
\(=\frac{99}{22}\)
~~~~~~~~~~~~~~~
\(A=11x\left(\frac{5}{11x16}+\frac{5}{16x21}+\frac{5}{21x26}+\frac{5}{26x31}+\frac{5}{31x36}+\frac{5}{36x41}\right)\)
\(A=11x\left(\frac{16-11}{11x16}+\frac{21-16}{16x21}+\frac{26-21}{21x26}+...+\frac{41-36}{36x41}\right)\)
\(A=11x\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+...+\frac{1}{36}-\frac{1}{41}\right)\)
\(A=11x\left(\frac{1}{11}-\frac{1}{41}\right)=11x\frac{30}{11x41}=\frac{30}{41}\)
A=\(\frac{55}{11.16}+\frac{55}{16.21}+...+\frac{55}{36.41}\)
A=\(11\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+...+\frac{1}{36}-\frac{1}{41}\right)\)
A=\(11\left(\frac{1}{11}-\frac{1}{41}\right)\)
A=\(11.\frac{30}{451}\)
A=\(\frac{30}{41}\)