Tìm x, biết” a) x+1/10 + x+1/11 + x+1/120 = x+1/13 + x+1/14 b) (x+4/2000) + (x+3/2001) = (x+2/2002) + (x+1/2003)

0 bình luận về “Tìm x, biết” a) x+1/10 + x+1/11 + x+1/120 = x+1/13 + x+1/14 b) (x+4/2000) + (x+3/2001) = (x+2/2002) + (x+1/2003)”

1. a) x+1/10 + x+1/11 + x+1/12 = x+1/13 + x+1/14

       x+1/10 +  x+1/11 +  x+1/12 –  x+ 1/13 – x+1/14 = 0

     ( x + 1).  (1/10 + 1/11 + 1/12 – 1/13 – 1/14) = 0

   Vì (1/10 + 1/11 + 1/12 – 1/13 – 1/14)  ≠ 0 nên:
   x + 1 = 0
   x = −1
   Vậy x=-10 

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2.    a) x+1/10 + x+1/11 + x+1/12 = x+1/13 + x+1/14

       x+1/10 +  x+1/11 +  x+1/12 –  x+ 1/13 – x+1/14 = 0

     ( x + 1).  (1/10 + 1/11 + 1/12 – 1/13 – 1/14) = 0

   Vì (1/10 + 1/11 + 1/12 – 1/13 – 1/14)  ≠ 0 nên:
   x + 1 = 0
   x = −1
   Vậy x=-10

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