Question

[kudo shinichi]

tìm x thuộc Z

a) 3x-4=-2x+5

b) 3(-4-2x) =3x+6

c) /3x-2/=2x-1

Answer 1

[Nguyễn Thái Thịnh]

a) 3x - 4 = -2x + 5

<=> 3x = -3x + 9

<=> 3x + 2x = 9

<=> 5x = 9

<=> x = 9/5

Answer 2

[Nguyễn Ngọc Linh]

\(\text{a) 3x-4=-2x+5}\)

\(3x-4=-2x+5\)

\(3x+2x=5+4\)

\(5x=9\)

\(\Rightarrow x=\frac{9}{5}\)

\(\text{b) 3(-4-2x) =3x+6}\)

\(-12-6x=3x+6\)

\(-6x-3x=6+12\)

\(-9x=18\)

\(\Rightarrow x=-2\)

\(\text{c) /3x-2/=2x-1}\)

\(\Rightarrow\orbr{\begin{cases}3x-2=2x-1\\3x-2=-\left(2x-1\right)\end{cases}\Leftrightarrow\orbr{\begin{cases}3x-2=2x-1\\3x-2=-2x+1\end{cases}}}\)

\(\Leftrightarrow\orbr{\begin{cases}3x-2x=-1+2\\3x+2x=1+2\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\5x=3\end{cases}}}\)\(\Leftrightarrow x\in\left\{1;\frac{3}{5}\right\}\)

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