Đáp án:
$a)
x \leq 2\\
b)
-1<x\leq -10$
Giải thích các bước giải:
$a)\frac{-15}{19}+\frac{x}{19}<\frac{x}{19}\leq \frac{13}{19}-\frac{11}{19}\\
\Leftrightarrow 19.\left ( \frac{-15}{19}+\frac{x}{19} \right )<19.\frac{x}{19}\leq 19.\left (\frac{13}{19}-\frac{11}{19} \right )\\
\Leftrightarrow -15+x<x \leq 13-11\\
\Leftrightarrow -15+x<x \leq 2\\
+) -15+x<x\Leftrightarrow x-x>-15\Leftrightarrow 0x>-15\Leftrightarrow \forall x \in \mathbb{R}\\
+) x \leq 2\\
b)
\frac{-7}{8}+\frac{5}{6}<\frac{x}{24}\leq \frac{-5}{12}\\
\Leftrightarrow 24.(\frac{-7}{8}+\frac{5}{6})<24.\frac{x}{24}\leq 24.\frac{-5}{12}\\
\Leftrightarrow -21+20<x \leq -10\\
\Leftrightarrow -1<x\leq -10$
