Question

1, Tìm số hữu tỉ x trong tỉ lệ thức

a, 0,4 : x = x : 0,9

b, \(^{13}\dfrac{1}{3}\): \(^{1\dfrac{1}{3}}\) = 26 : ( 2x - 1 )

c, 0,2 : \(^{1\dfrac{1}{5}}\) = \(\dfrac{2}{3}\): ( 6x + 7 )

d, \(\dfrac{37-x}{x+13}\) = 37

Answer 1

a: \(\dfrac{0.4}{x}=\dfrac{x}{0.9}\)

nên \(x^2=\dfrac{9}{25}\)

=>x=3/5 hoặc x=-3/5

b: \(\dfrac{26}{2x-1}=13\dfrac{1}{3}:1\dfrac{1}{3}\)

\(\Leftrightarrow\dfrac{26}{2x-1}=\dfrac{40}{3}:\dfrac{4}{3}=10\)

=>2x-1=13/5

=>2x=18/5

hay x=9/5

c: \(\Leftrightarrow\dfrac{2}{3}:\left(6x+7\right)=\dfrac{1}{5}:\dfrac{6}{5}\)

\(\Leftrightarrow\dfrac{2}{3}:\left(6x+7\right)=\dfrac{1}{6}\)

=>6x+7=4

=>6x=-3

hay x=-1/2

d: \(\dfrac{37-x}{x+13}=37\)

=>37(x+13)=37-x

=>37x+481=37-x

=>38x=-444

hay x=-222/19