a, \(=-\dfrac{2}{5}x^3y^2z^4\)
b, \(=\dfrac{1}{2}a^3b^2\)
c, \(=-\dfrac{5}{3}x^4y^5\)
a, 1/3x2yz . (-6/5)xyz3
= 1/3 . (-6/5) x2 . x . y. y . z. z3
= -2/5x3y2z4
b, 2ab . 1/4a2b
= 2 . 1/4 a.a2.b.b
= 1/2a3b2
c, -3(xy)2 . 5/9x2y3
= -3x2y2 . 5/9x2y3
= -3 . 5/9x2.x2.y2.y3
= -5/3x4y5







