1、下列计算是否正确?不正确的,指出错在哪里,并改正:
(1)3x42x2=6x6 ( )
(2)ab23abc=3a2b3 ( )
(3)4xy(-7xy)=-28xy ( )
(4)6a86a8=12a16 ( )
2、选择:
(1)下列运算中,正确的是 ( )
A、a10a5=a2B、(a3)4=a7 C、(x-y)2=x2-y2 D、4a3(-3a3)=-12a6
(2)若(mx4)(4xk)=-12x12,则适合条件的m, k的值应是 ( )
A、m=3, k=8B、m=-3, k=8 C、m=8, k=3 D、m=-3, k=3
3、计算:
(1) -3xy2xy(2) 3a2b2ababc2
(3) (-3ab)(-a2c)6ab2c(4) 2(x+y)3(x+y)2(x+y)5
(5) (2103) (3104)(-3105)(6) (-x)5(xy)2x3y
(7) (-3x2y)3xyz(-xy)2(8) [-2(x-y)2]2(y-x)3
(9) anb2(an+1b4)2 (10) (-2sn+1)4snt
拓展延伸
1、计算:
(1)(2an+2)(-3an-1)(2) (-1.2102)2(5103)3(2104)2
(3) 5x3y(-3y)2+(-6xy)2(-xy)+xy3(-4x2)(4)(32)10(25)10
2、已知:9an-3b2n与-2a3mb5-n的积与5a4b9是同类项,求m, n的值.