Câu hỏi của Mạc Hy

Question

giá trị nguyên của x thỏa mãn $\left(x-\frac{3}{5}\right).\left(x+\frac{2}{7}\right)< 0$  là x =

Xyz OLM · Accepted Answer

$\left(x-\frac{3}{5}\right).\left(x+\frac{2}{7}\right)< 0$$\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\x+\frac{2}{7}>0\end{cases}\text{hoặc}\hept{\begin{cases}x-\frac{3}{5}>0\x+\frac{2}{7}< 0\end{cases}}}$$\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\x>-\frac{2}{7}\end{cases}\text{hoặc}\hept{\begin{cases}x>\frac{3}{5}\x< -\frac{2}{7}\end{cases}}}$$\Rightarrow\orbr{\begin{cases}-\frac{2}{7}< x< \frac{3}{5}\x\in\varnothing\end{cases}}$$\Rightarrow-\frac{2}{7}< x< \frac{3}{5}$$\Rightarrow x=0$Vậy x = 0Câu trả lời: $\left(x-\frac{3}{5}\right).\left(x+\frac{2}{7}\right)< 0$$\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\x+\frac{2}{7}>0\end{cases}\text{hoặc}\hept{\begin{cases}x-\frac{3}{5}>0\x+\frac{2}{7}< 0\end{cases}}}$$\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\x>-\frac{2}{7}\end{cases}\text{hoặc}\hept{\begin{cases}x>\frac{3}{5}\x< -\frac{2}{7}\end{cases}}}$$\Rightarrow\orbr{\begin{cases}-\frac{2}{7}< x< \frac{3}{5}\x\in\varnothing\end{cases}}$$\Rightarrow-\frac{2}{7}< x< \frac{3}{5}$$\Rightarrow x=0$Vậy x = 0

Lily · Answer

$\left(x-\frac{3}{5}\right)\cdot\left(x+\frac{2}{7}\right)< 0$TH1 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\x+\frac{2}{7}>0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\x>-\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ }-\frac{2}{7}< x< \frac{3}{5}$TH2 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}>0\x+\frac{2}{7}< 0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x>\frac{3}{5}\x< -\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ Không xảy ra}$ Vì $x\in Z\text{ }\Rightarrow\text{ }x=0$Câu trả lời: $\left(x-\frac{3}{5}\right)\cdot\left(x+\frac{2}{7}\right)< 0$TH1 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\x+\frac{2}{7}>0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\x>-\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ }-\frac{2}{7}< x< \frac{3}{5}$TH2 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}>0\x+\frac{2}{7}< 0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x>\frac{3}{5}\x< -\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ Không xảy ra}$ Vì $x\in Z\text{ }\Rightarrow\text{ }x=0$

︵✰ßล∂ · Answer

$\left(x-\frac{3}{5}\right)\cdot\left(x+\frac{2}{7}\right)< 0$ TH1 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\x+\frac{2}{7}>0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\x>-\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ }-\frac{2}{7}< x< \frac{3}{5}$TH2 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}>0\x+\frac{2}{7}< 0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x>\frac{3}{5}\x< -\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ Không xảy ra}$ Vì $x\in Z\text{ }\Rightarrow\text{ }x=0$Câu trả lời: $\left(x-\frac{3}{5}\right)\cdot\left(x+\frac{2}{7}\right)< 0$ TH1 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}< 0\x+\frac{2}{7}>0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x< \frac{3}{5}\x>-\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ }-\frac{2}{7}< x< \frac{3}{5}$TH2 : $\Rightarrow\hept{\begin{cases}x-\frac{3}{5}>0\x+\frac{2}{7}< 0\end{cases}}$ $\Rightarrow\hept{\begin{cases}x>\frac{3}{5}\x< -\frac{2}{7}\end{cases}}$ $\Rightarrow\text{ Không xảy ra}$ Vì $x\in Z\text{ }\Rightarrow\text{ }x=0$

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