解(1)：4y×(-2xy²)
=4×(-2)×x×y×y²
=-8xy³
(2)：(3x²y)³×(-4x)
=3³×(x²)³×y³×(-4x)
=27×(x^6)×y³×(-4)×x ^表示乘方
=27×(-4)×(x^6)×x×y³
=-108(x^7)y³