Tìm x : a) (19.|x-1|+ 2 . $5^{2}$) : 14 = ( $(13-8)^{2}$ – $4^{2}$

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1. @Bơ

   `(19.|x-1|+2.5^2):14=((13-8)^2-4^2)`
   `(19.|x-1|+2.5^2):14=5^2-4^2`
   `(19.|x-1|+2.5^2):14=25-16`
   `(19.|x-1|+2.5^2):14=9`
   `(19.|x-1|+2.25):14=9`
   `19.|x-1|+50=126`
   `19.|x-1|=238-50`
   `19.|x-1|=76`
   `|x-1|=76:19`
   `|x-1|=4`
   `=>x-1=4 \text{hay}x-1=-4`
   `=>x=4+1\text{hay}x=-4+1`
   `=>x=5\text{hay}x=-3`

    

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2. a, (19.|x-1|+2.5^2):14 = (13-8)^2 – 4^2

   (19|x-1|+2.25):14=5^2-16

   (19|x-1|+50):14=25-16

   (19|x-1|+50):14=9

   19|x-1|+50=9.14

   19|x-1|+50=126

   19|x-1|=126-50

   19|x-1|=76

   |x-1|=76:19

   |x-1|=4

   => x-1=4 hoặc x-1=-4

   => x=4+1 hoặc x=-4+1

   => x=5 hoặc x=-3

   Vậy x ∈ {-3;5}

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