Question

tìm x biết

a | \(\frac{2}{5}x-\frac{1}{10}\) | + | \(\frac{1}{2}y-\frac{1}{3}\)| \(\le\)  0

b, |x| - x=0

Answer 1

a, \(\left|\frac{2}{5}x-\frac{1}{10}\right|+\left|\frac{1}{2}y-\frac{1}{3}\right|\le0\)

Vì giá trị tuyệt đối luôn luôn \(\ge0\)

=> \(\left|\frac{2}{5}x-\frac{1}{10}\right|+\left|\frac{1}{2}y-\frac{1}{3}\right|=0\)

=> \(\left|\frac{2}{5}x-\frac{1}{10}\right|=0\) hoặc \(\left|\frac{1}{2}y-\frac{1}{3}\right|=0\)

TH1: \(\frac{2}{5}x-\frac{1}{10}=0\)

                 \(\frac{2}{5}x=\frac{1}{10}\)

                     \(x=\frac{1}{10}.\frac{5}{2}=\frac{1}{4}\)

TH2: \(\frac{1}{2}y-\frac{1}{3}=0\)

                 \(\frac{1}{2}y=\frac{1}{3}\)

                      \(y=\frac{1}{3}.2=\frac{2}{3}\)

=> x có 2 nghiệm { 1/4; 2/3 }