Tìm x, biết 2 1/3:1/3=7/9:x

a, \(2\dfrac{1}{3}:\dfrac{1}{3}=\dfrac{7}{9}:x\)

\(\Rightarrow\dfrac{7}{9}:x=\dfrac{7}{3}\cdot3\)

\(\Rightarrow\dfrac{7}{9}:x=7\)

\(\Rightarrow x=\dfrac{1}{9}\)

b, \(x:\dfrac{1}{3}=\dfrac{12}{99}:\dfrac{15}{90}\)

\(\Rightarrow x:\dfrac{1}{3}=\dfrac{4}{33}\cdot\dfrac{3}{18}\)

\(\Rightarrow x:\dfrac{1}{3}=\dfrac{2}{99}\)

\(\Rightarrow x=\dfrac{2}{297}\)

c, \(\dfrac{4}{9}:x=3\dfrac{1}{3}:2,25\)

\(\Rightarrow\dfrac{4}{9}:x=\dfrac{10}{3}\cdot\dfrac{4}{9}\)

\(\Rightarrow\dfrac{4}{9}:x=\dfrac{40}{27}\)

\(\Rightarrow x=\dfrac{3}{10}\)

d, \(\dfrac{4}{3}:\dfrac{41}{99}=x:\dfrac{75}{90}\)

\(\Rightarrow x:\dfrac{5}{6}=\dfrac{4}{3}\cdot\dfrac{99}{41}\)

\(\Rightarrow x:\dfrac{5}{6}=\dfrac{132}{41}\)

\(\Rightarrow x=\dfrac{110}{41}\)

e, \(\dfrac{x-5}{7}=\dfrac{x+2}{3}\)

\(\Rightarrow3\left(x-5\right)=7\left(x+2\right)\)

\(\Rightarrow3x-15=7x+14\)

\(\Rightarrow7x-3x=-15-14\)

\(\Rightarrow4x=-29\)

\(\Rightarrow x=-\dfrac{29}{4}\)

f, \(\left(x-5\right)\cdot\left(x+2\right)=\left(x-3\right)\cdot\left(x+4\right)\)

\(\Rightarrow x^2+2x-5x-10=x^2+4x-3x-12\)

\(\Rightarrow x^2-3x-10=x^2+x-12\)

\(\Rightarrow x^2-x^2-3x-x=-12+10\)

\(\Rightarrow-4x=2\)

\(\Rightarrow x=-0,5\)