Question

1; tìm x:

a)\(\dfrac{1}{2}.x+\dfrac{3}{5}.\left(x-2\right)=3\)

Answer 1

Giải:

\(\dfrac{1}{2}.x+\dfrac{3}{5}.\left(x-2\right)=3\)

\(\Leftrightarrow\dfrac{1}{2}x+\dfrac{3}{5}x-\dfrac{6}{5}=3\)

\(\Leftrightarrow\dfrac{1}{2}x+\dfrac{3}{5}x=3+\dfrac{6}{5}\)

\(\Leftrightarrow\dfrac{11}{10}x=\dfrac{21}{5}\)

\(\Leftrightarrow x=\dfrac{21}{5}:\dfrac{11}{10}=\dfrac{42}{11}\)

Vậy ...

Answer 2

<=>\(\dfrac{x}{2}+\dfrac{3x}{5}-\dfrac{6}{5}=3\)

<=>\(\dfrac{5x}{10}+\dfrac{6x}{10}=\dfrac{30}{10}+\dfrac{12}{10}\)

<=>\(11x=42\)

<=>x=42/11

Answer 3

\(\dfrac{1}{2}.x+\dfrac{3}{5}.\left(x-2\right)=3\)

\(\Leftrightarrow\dfrac{1}{2}x+\dfrac{3}{5}x-\dfrac{6}{5}=3\)

\(\Leftrightarrow\dfrac{11}{10}x-\dfrac{6}{5}=3\)

\(\Rightarrow\dfrac{11}{10}x=3+\dfrac{6}{5}=\dfrac{21}{5}\)

\(\Rightarrow x=\dfrac{21}{5}:\dfrac{11}{10}\)

\(\Rightarrow x=\dfrac{210}{55}=\dfrac{42}{11}\)

Vậy \(x=\dfrac{42}{11}\)

Answer 4

Ta có : 1/2 * x + 3/5 * [ x - 2 ] = 3

⇒ 1/2 * x + 3/5 * x - 3/5 * 2 = 3

⇒ [ 1/2 + 3/5 ] * x - 3/5 * 2 = 3

⇒ [ 5/10 + 6/10 ] * x - 6/5 = 3

⇒ 11/10 * x - 6/5 = 3

⇒ 11/10 * x = 3 + 6/5

⇒ 11/10 * x = 21/5

⇒ x = 21/5 : 11/10

⇒ x = 21/5 * 10/11

⇒ x = 42/11

Vậy x = 42/11