a: \(3xy^3\cdot x^4y^2=3x^5y^2\)
b: \(\dfrac{4}{5}x^4y^2\cdot\left(-5\right)xy^3=-4x^5y^5\)
c: \(\dfrac{1}{7}x^2y\cdot\dfrac{2}{5}xy^4=\dfrac{2}{35}x^3y^5\)
a. 3xy3 . 2x4y
= 6x5y4
b. \(\dfrac{12}{15}x^4y^2.\left(-5\right)xy^3\)
= -4x5y5
c. \(\dfrac{-1}{7}x^2y.\dfrac{-2}{5}xy^4\)
= \(\dfrac{2}{35}x^3y^5\)