Thu gọn các đơn thức :
a) \(\left(\dfrac{a}{2}\right)^33xy\left(4a^2x^3\right)\left(\dfrac{13}{3}ay^2\right)\)
b)\(\left(2x^2y^3z^4\right)^k\left(-\dfrac{1}{2}xy^2\right)^2\)
c) \(\left(\dfrac{7}{3}x^2y^3\right)^{10}\left(\dfrac{3}{7}x^5y^4\right)^{10}\)