1, Tìm x: a, $\frac{4}{7}$ – ( 0,7 + x ) = $\frac{6}{7}$ b, ( $\frac{2}{3}$x – $\frac{1}{4}$ ) . $\frac{3}{2}$ = $\frac{3}{5}$

0 bình luận về “1, Tìm x: a, $\frac{4}{7}$ – ( 0,7 + x ) = $\frac{6}{7}$ b, ( $\frac{2}{3}$x – $\frac{1}{4}$ ) . $\frac{3}{2}$ = $\frac{3}{5}$”

1. $a.\dfrac{4}{7}-(0,7+x)=\dfrac{6}{7} \\⇔0,7+x=\dfrac{4}{7}-\dfrac{6}{7} \\⇔0,7+x=\dfrac{-2}{7} \\⇔x=\dfrac{-2}{7}-0,7 \\⇔x=\dfrac{-69}{70} \\Vậy\ x=\dfrac{-69}{70} \\b.\bigg(\dfrac{2}{3}x-\dfrac{1}{4}\bigg).\dfrac{3}{2}=\dfrac{3}{5} \\⇔\dfrac{2}{3}x-\dfrac{1}{4}=\dfrac{3}{5}÷\dfrac{3}{2} \\⇔\dfrac{2}{3}x-\dfrac{1}{4}=\dfrac{2}{5} \\⇔\dfrac{2}{3}x=\dfrac{2}{5}+\dfrac{1}{4} \\⇔\dfrac{2}{3}x=\dfrac{13}{20} \\⇔x=\dfrac{13}{20}:\dfrac{2}{3} \\⇔x=\dfrac{39}{40} \\Vậy\ x=\dfrac{39}{40}$

    

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2. Đáp án:

   a, $\frac{4}{7}$ – (0,7 + x) = $\frac{6}{7}$ 

   ⇔ 0,7+x = $\frac{4}{7}$ – $\frac{6}{7}$ 

   ⇔ 0,7 + x = $\frac{-2}{7}$ 

   ⇔          x= $\frac{-2}{7}$  – 0,7

   ⇔          x = $\frac{-69}{70}$ 

   b, ($\frac{2}{3}$ x – $\frac{1}{4}$ ). $\frac{3}{2}$ = $\frac{3}{5}$ 

   ⇔ $\frac{2}{3}$ x – $\frac{1}{4}$ = $\frac{3}{5}$ : $\frac{3}{2}$ 

   ⇔ $\frac{2}{3}$ x – $\frac{1}{4}$ = $\frac{2}{5}$ 

   ⇔ $\frac{2}{3}$ x = $\frac{2}{5}$ + $\frac{1}{4}$ 

   ⇔ $\frac{2}{3}$ x = $\frac{13}{20}$ 

   ⇔ x= $\frac{13}{20}$ : $\frac{2}{3}$ 

   ⇔ x=$\frac{39}{40}$ 

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