a) \(\sqrt{x+3}\ge5\) (ĐK: \(x\ge-3\))
\(\Leftrightarrow x+3\ge5^2\)
\(\Leftrightarrow x+3\ge25\)
\(\Leftrightarrow x\ge25-3\)
\(\Leftrightarrow x\ge22\left(tm\right)\)
b) \(\sqrt{-2x+1}>7\) (ĐK: \(x\le\dfrac{1}{2}\))
\(\Leftrightarrow-2x+1>7^2\)
\(\Leftrightarrow-2x+1>49\)
\(\Leftrightarrow-2x>49-1\)
\(\Leftrightarrow-2x>48\)
\(\Leftrightarrow x< -24\left(tm\right)\)
c) \(\sqrt{x}+9\le31\) (ĐK: \(x\ge0\))
\(\Leftrightarrow\sqrt{x}\le31-9\)
\(\Leftrightarrow\sqrt{x}\le22\)
\(\Leftrightarrow x\le22^2\)
\(\Leftrightarrow x\le484\)
Kết hợp với đk: \(0\le x\le484\)
d) \(\sqrt{3x-1}< 2\) (ĐK: \(x\ge\dfrac{1}{3}\))
\(\Leftrightarrow3x-1< 2^2\)
\(\Leftrightarrow3x-1< 4\)
\(\Leftrightarrow3x< 4+1\)
\(\Leftrightarrow3x< 5\)
\(\Leftrightarrow x< \dfrac{5}{3}\)
Kết hợp với đk: \(\dfrac{1}{3}\le x\le\dfrac{5}{3}\)
a: =>x+3>=25
=>x>=22
b: =>-2x+1>49
=>-2x>48
=>x<-24
c: =>căn x<=22
=>0<=x<=484
d: =>0<=3x-1<4
=>1<=3x<5
=>1/3<=x<5/3
