Question

Tìm x: (giải chi tiết giúp mình nha)

\(\frac{-1}{5}.\left(\frac{2x}{5}-1\right)=\frac{1}{7}\)( không sai đề đâu nha các bạn)

Answer 1

2x/5 - 1 = 1/7 : -1/5

2x/5 - 1 = -5/7

2x / 5    = -5/7 + 1

2x / 5    =2/7

=> 7( 2x ) = 2.5

=> 14x     = 10 

=> x         = 10 : 14

=> x         = 5/7

Answer 2

\(\frac{-1}{5}\times\left(\frac{2x}{5}-1\right)=\frac{1}{7}\)

\(\frac{2x}{5}-1=\frac{1}{7}\div\left(-\frac{1}{5}\right)\)

\(\frac{2x}{5}-1=\frac{1}{7}\times\left(-5\right)\)

\(\frac{2x}{5}-1=-\frac{5}{7}\)

\(\frac{2x}{5}=-\frac{5}{7}+1\)

\(\frac{2x}{5}=\frac{-5+7}{7}\)

\(\frac{2x}{5}=\frac{2}{7}\)

\(x=\frac{2}{7}\div\frac{2}{5}\)

\(x=\frac{2}{7}\times\frac{5}{2}\)

\(x=\frac{5}{7}\)