Question

Tìm x , biết :

\(2x+\dfrac{3}{4}=\dfrac{1}{2}\)

\(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

Answer 1

2x + 3/4=1/2

2x =1/2-3/4

2x =1/4

x = 1/4 : 2

x = 1/6

Answer 2

Lời giải:

a) \(2x+\dfrac{3}{4}=\dfrac{1}{2}\)

\(\Leftrightarrow2x=\dfrac{1}{2}-\dfrac{3}{4}\)

\(\Leftrightarrow2x=-\dfrac{1}{4}\)

\(\Leftrightarrow x=-\dfrac{1}{4}:2\)

\(\Leftrightarrow x=-\dfrac{1}{8}\)

Vậy ...

b) \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

\(\Leftrightarrow\dfrac{3}{4}+\dfrac{1}{4x}=\dfrac{2}{5}\)

\(\Leftrightarrow\dfrac{1}{4x}=\dfrac{2}{5}-\dfrac{3}{4}\)

\(\Leftrightarrow\dfrac{1}{4x}=-\dfrac{7}{20}\)

\(\Leftrightarrow4x=\dfrac{1}{-\dfrac{7}{20}}=-\dfrac{20}{7}\)

\(\Leftrightarrow x=-\dfrac{20}{7}:4=-\dfrac{5}{7}\)

Vậy ...

Answer 3

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

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

1/4 : x = -3/20

x = 1/4:-3/20

x = -5/3

Answer 4

a.

2x + \(\dfrac{3}{4}\) = \(\dfrac{1}{2}\)

2x = \(\dfrac{1}{2}\)-\(\dfrac{3}{4}\)= \(\dfrac{2}{4}\)-\(\dfrac{3}{4}\)

2x = \(\dfrac{1}{4}\)

x = \(\dfrac{1}{4}\):2

x = \(\dfrac{1}{8}\)

b.

\(\dfrac{3}{4}\)+\(\dfrac{1}{4}\):x=\(\dfrac{2}{3}\)

\(\dfrac{1}{4}\):x=\(\dfrac{2}{3}\)-\(\dfrac{3}{4}\)=\(\dfrac{8}{12}\)-\(\dfrac{9}{12}\)

\(\dfrac{1}{4}\):x=-\(\dfrac{1}{12}\)

x= \(\dfrac{1}{4}\) : -\(\dfrac{1}{12}\)

x=\(\dfrac{1}{4}\)*\(\left(-12\right)\)

x= -3