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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: tính : A= (-1/91) + (-1/247) + (-1/475) + (-1/775) + (-1/1147)

Toán Lớp 6: tính : A= (-1/91) + (-1/247) + (-1/475) + (-1/775) + (-1/1147)

Comments ( 2 )

  1. A = (-1)/91 + (-1)/247 + (-1)/475 + (-1)/775 + (-1)/1147
    A = 1/6 . 6 . ((-1)/91 + (-1)/247 + (-1)/475 + (-1)/775 + (-1)/1147)
    A = 1/6 . (-6)/91 + (-6)/247 + (-6)/475 + (-6)/1147
    A = 1/6 . (-6)/(7.13) + (-6)/(13.19) + (-6)/(19.25) + (-6)/(31.37)
    A = 1/6 . ((-1)/7 – (-1)/13 + (-1)/13 – (-1)/19 + … + (-1)/31 – (-1)/37)
    A = 1/6 . ((-1)/7 – (-1)/37)
    A = 1/6 . ((-1)/7 + 1/37)
    A = 1/6 . (-30)/259
    A = (-5)/259
     

  2. Giải đáp:
    A = $\frac{-5}{259}$ 
    Lời giải và giải thích chi tiết:
    A = $\frac{-1}{91}$ + $\frac{-1}{247}$ + $\frac{-1}{475}$ + $\frac{-1}{775}$ + $\frac{-1}{1147}$
       = $\frac{1}{6}$ . 6 . ( $\frac{-1}{91}$ + $\frac{-1}{247}$ + $\frac{-1}{475}$ + $\frac{-1}{775}$ +  $\frac{-1}{1147}$)
       = $\frac{1}{6}$ . ( $\frac{-6}{91}$ + $\frac{-6}{247}$ + $\frac{-6}{475}$ + $\frac{-6}{775}$ + $\frac{-6}{1147}$ )
       = $\frac{1}{6}$ . ( $\frac{-6}{7.13}$ + $\frac{-6}{13.19}$ + $\frac{-6}{19.25}$ + $\frac{-6}{25.31}$ + $\frac{-6}{31.37}$ )
       = $\frac{1}{6}$ . ( $\frac{-1}{7}$ – $\frac{-1}{13}$ + $\frac{-1}{13}$ – $\frac{-1}{19}$ + $\frac{-1}{19}$ – $\frac{-1}{25}$ + $\frac{-1}{25}$ – $\frac{-1}{31}$ + $\frac{-1}{31}$ – $\frac{-1}{37}$ )
       = $\frac{1}{6}$ . ($\frac{-1}{7}$ – $\frac{-1}{37}$ )
       = $\frac{1}{6}$ . $\frac{-30}{259}$
    A = $\frac{-5}{259}$ 

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222-9+11+12:2*14+14 = ? ( )

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