Tính
a, \(\left(\dfrac{3}{7}+\dfrac{1}{2}\right)^2\)

b, \(\left(\dfrac{3}{4}-\dfrac{5}{6}\right)^2\)

c, \(\dfrac{5^4.20^4}{25^5.4^5}\)

d, \(\left(\dfrac{-10}{3}\right)^5.\left(\dfrac{-6}{5}\right)^4\)

Tìm tập hợp các số nguyên x, biết rằng:
\(4\dfrac{5}{9}:2\dfrac{5}{18}-7< \)            \(< \left(3\dfrac{1}{5}:3,2+4,5.1\dfrac{31}{45}\right):\left(-21\dfrac{1}{2}\right)\)

Tìm x:
\(2x.\left(x-\dfrac{1}{7}\right)=0\)

\(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)