Question

1. Tìm x trong tỉ lệ thức sau :

a) 0,75 : 4,5 = \(\dfrac{1}{15}\) : (2x)

b) \(\dfrac{-5}{x-2}\) = \(\dfrac{3}{-9}\) c) \(\dfrac{-2}{3}\) : x = \(\dfrac{1}{2}\) : \(\dfrac{3}{4}\)

HELP ME!

Answer 1

a) \(0,75:4,5=\dfrac{1}{15}:\left(2x\right)\)

\(\Rightarrow\) \(\dfrac{1}{6}=\dfrac{1}{30}:x\)

\(\Rightarrow\) \(x=\dfrac{1}{5}\)

Answer 2

a. \(0,75:4,5=\dfrac{1}{15}:\left(2x\right)\)

\(\Leftrightarrow\dfrac{1}{15}:\left(2x\right)=0,75:4,5\)

\(\Rightarrow\dfrac{1}{15}:\left(2x\right)=\dfrac{1}{6}\)

\(\Rightarrow2x=\dfrac{1}{15}:\dfrac{1}{6}=\dfrac{2}{5}\)

\(\Rightarrow x=\dfrac{2}{5}:2=\dfrac{1}{5}\)

Vậy...

b. \(\dfrac{-5}{x-2}=\dfrac{3}{-9}\)

\(\Leftrightarrow\left(x-2\right).3=\left(-5\right).\left(-9\right)\)

\(\Rightarrow\left(x-2\right).3=45\)

\(\Rightarrow\left(x-2\right)=45:3=15\)

\(\Rightarrow x=15+2=17\)

Vậy...

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

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

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

Vậy...

Answer 3

b) \(\dfrac{-5}{x-2}=\dfrac{3}{-9}\)

\(\Rightarrow45=3\left(x-2\right)\)

\(\Rightarrow45=3x-6\)

\(\Rightarrow3x=51\)

\(\Rightarrow x=17\)

Answer 4

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

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

\(\Rightarrow x=-1\)

Answer 5

a) \(0,75:4,5=\dfrac{1}{15}:\left(2x\right)\)

\(\dfrac{1}{6}=\dfrac{1}{15}:2x\)

\(\Leftrightarrow\) \(\dfrac{1}{15}:2x=\dfrac{1}{6}\)

\(2x=\dfrac{1}{15}:\dfrac{1}{6}\)

\(2x=\dfrac{2}{5}\)

\(\Rightarrow x=\dfrac{1}{5}\)