a) Đặt A= 2x-4
Thay \(x=\frac{-1}{3}\), ta có: \(A=2.\frac{-1}{3}-4\)
\(\Leftrightarrow\) \(A=\frac{-2}{3}-4\)
\(\Leftrightarrow A=\frac{-2}{3}-\frac{12}{3}\)
\(\Leftrightarrow A=\frac{-14}{3}\)
\(\Rightarrow m=\frac{\frac{-14}{3}}{x+3}\)
\(\Leftrightarrow\frac{-14}{3}:\left(\frac{-1}{3}+3\right)\)
\(\Leftrightarrow m=\frac{-14}{3}:\frac{8}{3}=\frac{-14}{3}.\frac{3}{8}=\frac{-7}{4}\)
Vậy: m=\(\frac{-7}{4}\)
c) Để m có giá trị nguyên thì: \(2x-4⋮x+3\)
\(\Leftrightarrow2x+6-10⋮x+3\)
\(\Leftrightarrow2\left(x+3\right)-10⋮x+3\)
Do \(2\left(x+3\right)⋮x+3\) \(\Rightarrow10⋮x+3\)
\(\Rightarrow x+3\in\left\{-10;-5;-2;-1;1;2;5;10\right\}\)
\(\Rightarrow x\in\left\{-13;-8;-5;-4;-2;-1;2;7\right\}\)
Vậy:..............
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