a: =>4/3x=7/9-4/9=1/3
=>x=1/4
b: =>5/2-x=9/14:(-4/7)=-9/8
=>x=5/2+9/8=29/8
c: =>3x+3/4=8/3
=>3x=23/12
hay x=23/36
d: =>-5/6-x=7/12-4/12=3/12=1/4
=>x=-5/6-1/4=-10/12-3/12=-13/12
\(d,-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)
\(\Leftrightarrow-\dfrac{5}{6}-x=\dfrac{7}{12}+\dfrac{-4}{12}\)
\(\Leftrightarrow-\dfrac{5}{6}-x=\dfrac{1}{4}\)
\(\Leftrightarrow-x=-\dfrac{5}{6}-\dfrac{1}{4}\)
\(\Leftrightarrow-x=-\dfrac{13}{12}\)
\(\Leftrightarrow x=\dfrac{13}{12}\)
\(c,3x+\dfrac{3}{4}=2\dfrac{2}{3}\)
\(\Leftrightarrow3x+\dfrac{3}{4}=\dfrac{8}{3}\)
\(\Leftrightarrow3x=\dfrac{8}{3}-\dfrac{3}{4}\)
\(\Leftrightarrow3x=\dfrac{23}{12}\)
\(\Leftrightarrow x=\dfrac{23}{12}:3\)
\(\Leftrightarrow x=\dfrac{23}{36}\)
\(b,\left(\dfrac{5}{2}-x\right)\left(-\dfrac{4}{7}\right)=\dfrac{9}{14}\)
\(\Leftrightarrow\dfrac{5}{2}-x=\dfrac{9}{14}:\left(-\dfrac{4}{7}\right)\)
\(\Leftrightarrow\dfrac{5}{2}-x=-\dfrac{9}{8}\)
\(\Leftrightarrow x=\dfrac{5}{2}+\dfrac{9}{8}\)
\(\Leftrightarrow x=\dfrac{29}{8}\)
\(a,\dfrac{4}{9}+\dfrac{4}{3}x=\dfrac{7}{9}\)
\(\Leftrightarrow\dfrac{4}{3}x=\dfrac{7}{9}-\dfrac{4}{9}\)
\(\Leftrightarrow\dfrac{4}{3}x=\dfrac{1}{3}\)
\(\Leftrightarrow x=\dfrac{1}{3}:\dfrac{4}{3}\)
\(\Leftrightarrow x=\dfrac{1}{4}\)
a, 4/9 + 4/3x = 7/9
=>4/3x = 7/9 - 4/9
=>4/3x = 3/9
=>x = 3/9 : 4/3
=>x = 3/9 . 3/4
=>x = 1/4
Vậy x = 1/4
b, (5/2 - x).(-4/7) = 9/14
=>5/2 - x = 9/14 : (-4/7)
=>5/2 - x = -9/8
=>x = 5/2 - (-9/8)
=>x = 5/2 + 9/8
=>x = 20/8 + 9/8
=>x = 29/8
Vậy...