Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a) \(x\in B\left(15\right)=\left\{0;15;30;45;60;65...\right\}\)
mà \(\left(40\le x\le70\right)\)
\(\Rightarrow x\in\left\{45;60;65\right\}\)
b) \(x⋮12\Rightarrow x\in B\left(12\right)=\left\{0;12;24;...\right\}\)
mà \(0< x\le30\)
\(\)\(\Rightarrow x\in\left\{12;24\right\}\)
c) \(6⋮\left(x-1\right)\Rightarrow\left(x-1\right)\in B\left(6\right)=\left\{0;6;12;18;24;30;...\right\}\)
\(\Rightarrow x\in\left\{1;7;13;19;25;31;...\right\}\)
a) \(\left(x+5\right)\left(3x-12\right)>0\)
\(\left(x+5\right).3.\left(x-4\right)>0\)
\(\Rightarrow\hept{\begin{cases}x+5>0\\x-4>0\end{cases}}\) hoặc \(\hept{\begin{cases}x+5< 0\\x-4< 0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x>-5\\x>4\end{cases}}\) hoặc \(\hept{\begin{cases}x< -5\\x< 4\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x>4\\x< -5\end{cases}}\)
vậy...
b: \(x+1⋮x-2\)
\(\Leftrightarrow x-2+3⋮x-2\)
\(\Leftrightarrow x-2\in\left\{1;-1;3;-3\right\}\)
hay \(x\in\left\{3;1;5;-1\right\}\)
c: \(\Leftrightarrow2x-1\in\left\{12;24;36;48\right\}\)
\(\Leftrightarrow x\in\left\{\dfrac{13}{2};\dfrac{25}{2};\dfrac{37}{2};\dfrac{49}{2}\right\}\)
d: \(\Leftrightarrow n+3+2⋮n+3\)
\(\Leftrightarrow n+3\in\left\{1;-1;2;-2\right\}\)
hay \(n\in\left\{-2;-4;-1;-5\right\}\)
e: \(2n-1⋮3n+6\)
\(\Leftrightarrow6n-3⋮3n+6\)
\(\Leftrightarrow6n+12-15⋮3n+6\)
\(\Leftrightarrow3n+6\in\left\{1;-1;3;-3;5;-5;15;-15\right\}\)
hay \(n\in\left\{-\dfrac{5}{3};-\dfrac{7}{3};-1;-3;-\dfrac{1}{3};-\dfrac{11}{3};3;-7\right\}\)