Tìm x. Biết (x 2/3 )³ = 1/27 (x + 1/2 ) ² = 1/6 60% x + 2/3x = 76

2 bình luận về “Tìm x. Biết (x 2/3 )³ = 1/27 (x + 1/2 ) ² = 1/6 60% x + 2/3x = 76”

1. #Aridoto

   a,(x-2/3)^3=1/27

   ↔(x-2/3)^3=(1/3)^3

   ↔x-2/3=1/3

   ↔x=1/3+2/3

   ↔x=1

   b,(x+1/2)^2=1/6

   ↔(x+1/2)^2=(\sqrt{6}/6)^2

   TH1:

   x+1/2=\sqrt{6}/6

   ↔x=\sqrt{6}/6-1/2

   ↔x=-7/12

   TH2:

   x+1/2=(-\sqrt{6})/6

   ↔x=(-\sqrt{6})/6-1/2

   ↔x=(-3-\sqrt{6})/6

   c,60%x+2/3x=76

   ↔3/5x+2/3x=76

   ↔19/15x=76

   ↔x=76:19/15

   ↔x=60

   Trả lời
2. ( x – $\frac{2}{3}$ ) ³ = $\frac{1}{27}$ 

   ⇒ ( x – $\frac{2}{3}$ ) ³ = ( $\frac{1}{3}$  ) ³

   ⇒ x – $\frac{2}{3}$ = $\frac{1}{3}$ 

   ⇒ x = 1

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   ( x + $\frac{1}{2}$ ) ² = $\frac{1}{6}$ 

   ⇒ x² + $\frac{1}{4}$ = $\frac{1}{6}$ 

   ⇒ x² = $\frac{1}{12}$

   ⇒ x =  $\sqrt{\frac{1}{12}}$

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   60% x + $\frac{2}{3}$ x = – 76

   ⇒ x  ( $\frac{3}{5}$ + $\frac{2}{3}$ ) = – 76

   ⇒ x $\frac{19}{15}$ = – 76

   ⇒ x = -76$\frac{15}{19}$

    

   Trả lời