\(A=\frac{\frac{1}{3}-0,25+\frac{1}{5}}{\frac{7}{6}-0,875+0,7}\)

\(=\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)

\(=\frac{2\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}{7\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}\)

\(=\frac{2}{7}\)

1. Tìm x, y∈ Q

a) (x+5)(3x-y) =0

b) (x-4)(y²-x) =0

c) (x+y)² + (2x-y)² =0

2. Tìm x ∈Q

a) x+2x−3 >0

b) 4x² - x <0

                             Giải chi tiết giúp mình nhé!!!!!!!