Question

Tập nghiệm của bất pt

a) \(\sqrt{x-2017}>\sqrt{2017-x}\)

b) \(\dfrac{2x^2-3x+4}{x^2+3}>2\)

c) \(3-2x+\sqrt{2-x}< x+\sqrt{2-x}\)

Answer 1

a, ĐK: \(x=2017\)

\(\sqrt{x-2017}>\sqrt{2017-x}\)

\(\Leftrightarrow\left\{{}\begin{matrix}2017-x\ge0\\x-2017>2017-x\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x\le2017\\x>2017\end{matrix}\right.\)

\(\Rightarrow S=\varnothing\)

Answer 2

b, \(\dfrac{2x^2-3x+4}{x^2+3}>2\)

\(\Leftrightarrow2x^2-3x+4>2x^2+6\)

\(\Leftrightarrow x< -\dfrac{2}{3}\)

\(\Rightarrow S=\left(-\infty;-\dfrac{2}{3}\right)\)

Answer 3

c, ĐK: \(x\le2\)

\(3-2x+\sqrt{2-x}< x+\sqrt{2-x}\)

\(\Leftrightarrow3-2x+\sqrt{2-x}< x+\sqrt{2-x}\)

\(\Leftrightarrow3x>3\)

\(\Leftrightarrow x>1\)

\(\Rightarrow S=(1;2]\)