Question

Tìm x thuộc Q, biết :

1) \(\frac{3}{4}x-\frac{1}{3}=\frac{2}{3}x-\frac{3}{5}\)

2) \(\left|x-3\right|=x\)

Answer 1

đề là x ∈ Z hay N

Answer 2

1) \(\frac{3}{4}x-\frac{1}{3}=\frac{2}{3}x-\frac{3}{5}\)

⇒ \(\frac{3}{4}x-\frac{2}{3}x=-\frac{3}{5}+\frac{1}{3}\)

⇒ \(\frac{1}{12}x=-\frac{4}{15}\)

⇒ x = \(-\frac{16}{5}\)

2) |x-3| = x

⇒ |x - 3| - x = 0

⇒ \(\left[{}\begin{matrix}x-3-x=0\\-\left(x-3\right)-x=0\end{matrix}\right.\)

⇒ \(\left[{}\begin{matrix}-3=0\\-2x+3=0\end{matrix}\right.\)

⇒ \(\left[{}\begin{matrix}-3=0\\-2x=-3\end{matrix}\right.\)

⇒ \(\left[{}\begin{matrix}-3=0\left(loại\right)\\x=\frac{3}{2}\left(nhận\right)\end{matrix}\right.\)

⇒ \(x=\frac{3}{2}\)

Answer 3

1) \(\frac{3}{4}x-\frac{1}{3}=\frac{2}{3}x-\frac{3}{5}\)

=> \(\frac{3}{4}x-\frac{2}{3}x=\frac{1}{3}-\frac{3}{5}\)

=> \(\frac{1}{12}x=-\frac{4}{15}\)

=> x = \(-\frac{4}{15}:\frac{1}{12}\)

=> \(x=-\frac{16}{5}\)