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27 tháng 4 2017

a) \(2\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|-\dfrac{3}{2}=\dfrac{1}{5}\)

\(2\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{1}{5}+\dfrac{3}{2}\)

\(2\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{17}{10}\)

\(\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{17}{10}:2\)

\(\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|=\dfrac{17}{20}\)

\(\circledast\)TH1: \(\dfrac{1}{2}x-\dfrac{1}{3}=\dfrac{17}{20}\)

\(\dfrac{1}{2}x=\dfrac{17}{20}+\dfrac{1}{3}\)

\(\dfrac{1}{2}x=\dfrac{71}{60}\)

\(x=\dfrac{71}{60}:\dfrac{1}{2}\)

\(x=\dfrac{71}{30}\)

\(\circledast\)TH2: \(\dfrac{1}{2}x-\dfrac{1}{3}=-\dfrac{17}{20}\)

\(\dfrac{1}{2}x=-\dfrac{17}{20}+\dfrac{1}{3}\)

\(\dfrac{1}{2}x=-\dfrac{31}{60}\)

\(x=-\dfrac{31}{60}:\dfrac{1}{2}\)

\(x=-\dfrac{31}{30}\)

Vậy \(x\in\left\{\dfrac{71}{30};-\dfrac{31}{30}\right\}\).

b) \(\dfrac{3}{4}-2\left|2x-\dfrac{2}{3}\right|=2\)

\(2\left|2x-\dfrac{2}{3}\right|=\dfrac{3}{4}-2\)

\(2\left|2x-\dfrac{2}{3}\right|=-\dfrac{5}{4}\)

\(\left|2x-\dfrac{2}{3}\right|=-\dfrac{5}{4}:2\)

\(\left|2x-\dfrac{2}{3}\right|=-\dfrac{5}{8}\) (vô lí)

Vậy \(x\in\varnothing \).

c) \(\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)

\(\circledast\)TH1: \(3x-1=0\)

\(3x=0+1\)

\(3x=1\)

\(x=\dfrac{1}{3}\)

\(\circledast\)TH2: \(-\dfrac{1}{2}x+5=0\)

\(-\dfrac{1}{2}x=0-5\)

\(-\dfrac{1}{2}x=-5\)

\(x=-5:\left(-\dfrac{1}{2}\right)\)

\(x=10\)

Vậy \(x\in\left\{\dfrac{1}{3};10\right\}\).

27 tháng 4 2017

BẠN nào nhanh MÌnh tick cho