Question

a) \(\dfrac{2}{15}\cdot x-x=30\%\)

b) \(\dfrac{x}{2}\cdot\dfrac{x}{3}=\dfrac{5}{6}\)

Answer 1

a)\(\dfrac{2}{15}x-x=30\%\)

<=>x\(\left(\dfrac{2}{15}-1\right)=\dfrac{30}{100}\)

<=>\(-\dfrac{13}{15}x=\dfrac{3}{10}\)

<=>x=\(\dfrac{3}{10}\cdot\left(-\dfrac{15}{13}\right)\)

<=>x=\(-\dfrac{9}{26}\)

Vậy tập nghiệm S={\(-\dfrac{9}{26}\)}

b)\(\dfrac{x}{2}\cdot\dfrac{x}{3}=\dfrac{5}{6}\)

<=>\(\dfrac{x^2}{6}=\dfrac{5}{6}\)

<=>x²=5

<=>x=\(_-^+\sqrt{5}\)

Vậy tập nghiệm S={\(_-^+\sqrt{5}\)}

Answer 2

a, \(\dfrac{2}{15}x-x=30\%\)

\(\Rightarrow\left(\dfrac{2}{15}-1\right)x=\dfrac{3}{10}\)

\(\Rightarrow\dfrac{-13}{15}x=\dfrac{3}{10}\)

\(\Rightarrow x=\dfrac{3}{10}.\dfrac{-15}{13}\)

\(\Rightarrow x=\dfrac{-9}{26}\)Lời giải:

b, \(\dfrac{x}{2}.\dfrac{x}{3}=\dfrac{5}{6}\)

\(\Rightarrow\dfrac{x.x}{2.3}=\dfrac{5}{6}\)

\(\Rightarrow\dfrac{x^2}{6}=\dfrac{5}{6}\)

\(\Rightarrow x^2=5\)

\(\Rightarrow x=\pm\sqrt{5}\)