Question

Tìm x biết :

a) \(2x.\left(x-\frac{1}{7}\right)=0\)           b)\(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)

Answer 1

b ) 3/4 + 1/4 : x = 2/5

              1/4 : x = 2/5 - 3/4

              1/4 : x = -7/20

                      x = 1/4 : -7/20

                      x = -5/7

Answer 2

a,2x. (x-1/7)=0 =>\(\orbr{\begin{cases}x=0\\x-\frac{1}{7}=0\end{cases}}\)<=>\(\orbr{\begin{cases}x=0\\x=\frac{1}{7}\end{cases}}\)

Answer 3

b, 3/4 +1/4:x = 2/5

=> 1/4:x = 2/5 - 3/4

<=> 1/4:x = -7/20

<=> x= 1/4 : -7/20

      x = 1/4 . -20/7

     x = -5/7

Answer 4

b ) Ta có: 3/4 + 1/4 : x = 2/5

       =>        1/4 : x = 2/5 - 3/4

        =>       1/4 : x = -7/20

       =>               x = 1/4 : -7/20

       =>               x = -5/7