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\(\dfrac{2727}{3131}=\dfrac{27.101}{31.101}=\dfrac{27}{31}\)
⇒\(\dfrac{27}{31}=\dfrac{2727}{3131}\)
\(\dfrac{27}{31}=\dfrac{27\times101}{31\times101}=\dfrac{2727}{3131}\)
\(\frac{27}{31}=\frac{27x10101}{31x10101}=\frac{272727}{313131}\)
`#3107.101107`
`a)`
Ta có:
\(\dfrac{2727}{3131}=\dfrac{2727\div27}{3131\div31}=\dfrac{27}{31}\)
Vì \(\dfrac{27}{31}=\dfrac{27}{31}\)
\(\Rightarrow\dfrac{27}{31}=\dfrac{2727}{3131}\)
`b)`
Ta có:
\(\dfrac{11}{31}=1-\dfrac{20}{31}=1-\dfrac{200}{310}\)
\(\dfrac{111}{311}=1-\dfrac{200}{311}\)
Vì \(\dfrac{200}{310}>\dfrac{200}{311}\)
\(\Rightarrow1-\dfrac{200}{310}< 1-\dfrac{200}{311}\)
\(\Rightarrow\dfrac{11}{31}< \dfrac{111}{311}.\)
\(a,\dfrac{2727}{3131}=\dfrac{2727:101}{3131:101}=\dfrac{27}{31}\\ Vậy:\dfrac{27}{31}=\dfrac{2727}{3131}\)
27 x \(\left(\frac{171717}{272727}+\frac{373737}{363636}\right)\)
= 27 x \(\left(\frac{17}{27}+\frac{37}{36}\right)\)
= 27 x \(\frac{17}{27}\)+ 27 x \(\frac{37}{36}\)
= 17 + 27,75
= 44,75
a) \(\frac{1212}{1515}\):\(\frac{2727}{2525}\)
= \(\frac{1212}{1515}\)* \(\frac{2525}{2727}\)
= \(\frac{101.12}{101.15}\)* \(\frac{101.25}{101.27}\)
= \(\frac{12}{15}\). \(\frac{25}{27}\)
= \(\frac{20}{27}\)
b) ban co the viet ro hon de bai dc ko?
Bài làm
Ta đặt M=1/3+1/7+1/13+1/21+1/31+1/43+1/57+1/73+1/91
Vậy M<1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
M< 1/2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10
M< (1-1/2) +(1/2-1/3) +(1/3-1/4) +(1/4-1/5) +(1/5-1/6) +(1/6-1/7) +(1/7-1/8) +(1/8-1/9) +(1/9-1/10)
M< 1-1/10 < 9/10 (1)
Vì 9/10 < 1 (2)
Từ(1) và (2) ta có : 1/3+1/7+1/13+1/21+1/31+1/43+1/57+1/73+1/91<1
\(\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)
\(\frac{27}{31}=\frac{27.101}{31.101}=\frac{27.10101}{31.10101}\)
\(\frac{27}{31}=\frac{27}{31}=\frac{27}{31}\)
\(\Rightarrow\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)
\(\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)
\(\frac{27}{31}=\frac{27\cdot101}{31\cdot101}=\frac{27\cdot10101}{31\cdot10101}\)
\(\Rightarrow\frac{27}{31}=\frac{2727}{3131}=\frac{272727}{313131}\)