Question

Answer 1

a) \(đk:x\ge\dfrac{1}{3}\)

\(pt\Leftrightarrow3x-1=4\Leftrightarrow3x=5\Leftrightarrow x=\dfrac{5}{3}\left(tm\right)\)

b) \(đk:x\ge7\)

\(pt\Leftrightarrow\sqrt{\left(2x-3\right)^2}=x-7\)

\(\Leftrightarrow\left|2x-3\right|=x-7\)

\(\Leftrightarrow2x-3=x-7\)(do \(x\ge7\))

\(\Leftrightarrow x=-4\left(ktm\right)\)

Vậy \(S=\varnothing\)

c) \(đk:x\ge-7\)

\(pt\Leftrightarrow4\sqrt{x+7}-2\sqrt{x+7}+\sqrt{x+7}=12\)

\(\Leftrightarrow3\sqrt{x+7}=12\)

\(\Leftrightarrow\sqrt{x+7}=4\Leftrightarrow x+7=16\Leftrightarrow x=9\left(tm\right)\)