1. 口算:
(1)$6x^{2}\cdot 3xy^{2}=$
$18x^{3}y^{2}$
; (2)$2x^{2}y\cdot \frac {3}{2}xy=$
$3x^{3}y^{2}$
;
(3)$2ab^{2}\cdot (-5ab^{4})=$
$-10a^{2}b^{6}$
; (4)$(2.5×10^{9})×(-0.8×10^{4})=$
$-2× 10^{13}$
.
答案：1.(1)$18x^{3}y^{2}$ (2)$3x^{3}y^{2}$ (3)$-10a^{2}b^{6}$ (4)$-2× 10^{13}$
2. 计算:
(1)$(2x)^{3}\cdot (-5xy^{2})$; (2)$5x^{2}y\cdot (-2xy^{2})^{3}$;
(3)$2x^{2}y\cdot (-4xy^{3}z)$; (4)$(-\frac {1}{3}x^{2}y)^{3}\cdot (-2xy^{2}z)^{2}$;
(5)$(-3ab^{3})^{2}\cdot (-a^{2}b)$; (6)$(-\frac {1}{2}a^{2}b^{3})^{3}\cdot (-2a^{2}b)^{2}$;
(7)$(-2×10^{5})^{2}÷(8×10^{5})$; (8)$3x^{3}y^{3}\cdot (-\frac {2}{3}x^{2}y^{2})+(-\frac {1}{3}x^{2}y)^{3}\cdot 9xy^{2}$.
答案：2.(1)$-40x^{4}y^{2}$ (2)$-40x^{5}y^{7}$ (3)$-8x^{3}y^{4}z$
(4)$-\frac{4}{27}x^{8}y^{7}z^{2}$ (5)$-9a^{4}b^{7}$ (6)$-\frac{1}{2}a^{10}b^{11}$
(7)$5× 10^{4}$ (8)$-2x^{5}y^{5}-\frac{1}{3}x^{7}y^{5}$
