a) \(4x+5\ge7\)
\(\Leftrightarrow4x\ge3\)
\(\Leftrightarrow x\ge\frac{3}{4}\)
Vậy BPT có nghiệm \(x\ge\frac{3}{4}\)
b) \(\frac{x-1}{4}-1>\frac{x+1}{3}+8\)
\(\Leftrightarrow\frac{x-1}{4}-\frac{x+1}{3}>8+1\)
\(\Leftrightarrow\frac{3\left(x-1\right)}{3.4}-\frac{4\left(x+1\right)}{4.3}>9\)
\(\Leftrightarrow\frac{3x-3}{12}-\frac{4x+4}{12}>9\)
\(\Leftrightarrow\frac{3x-3-4x-4}{12}>9\)
\(\Leftrightarrow-x-7>108\)
\(\Leftrightarrow-7-108>x\)
<=> -115>x
Vậy BPT có nghiệm là x<-115
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