Question

Tìm x trong tỉ lệ thức

a.\(\dfrac{-x}{112}=\dfrac{-7,5}{7}\)

b.\(\dfrac{\dfrac{7}{5}}{1,6}=\dfrac{x}{1,9}\)

Giúp với m.n ơi

Answer 1

a) \(\dfrac{-x}{112}=\dfrac{-7,5}{7}\Leftrightarrow7.\left(-x\right)=-7,5.112\Leftrightarrow-7x=-840\Leftrightarrow x=\dfrac{-840}{-7}=120\)

vậy \(x=120\)

b) \(\dfrac{\dfrac{7}{5}}{1,6}=\dfrac{x}{1,9}\Leftrightarrow1,6.x=\dfrac{7}{5}.1,9\Leftrightarrow1,6x=\dfrac{133}{50}\Leftrightarrow x=\dfrac{133}{50.1,6}=\dfrac{133}{80}\)

vậy \(x=\dfrac{133}{80}\)

Answer 2

a. \(\dfrac{-x}{112}=\dfrac{-7,5}{7}\)

\(\Leftrightarrow\left(-7,5\right).112=\left(-x\right)7\)

\(\Leftrightarrow-840=\left(-x\right)7\)

\(\Leftrightarrow-x=\left(-840\right):7\)

\(\Leftrightarrow-x=-120\)

Vậy ...........

b. \(\dfrac{\dfrac{7}{5}}{1,6}=\dfrac{x}{1,9}\)

\(\Leftrightarrow\dfrac{1,4}{1,6}=\dfrac{x}{1,9}\)

\(\Leftrightarrow1,6.x=1,4.1,9\)

\(\Leftrightarrow1,6x=2,66\)

\(\Leftrightarrow x=2,66:1,6\)

\(\Leftrightarrow x=1,6625\)

Vậy ...