Question

化简

3 a2 +3 3 ab +9 3 b2

( 3 a )4-27 3 a b

÷

3 a

3 a -3 3 b

-a-

2

3

．

Answer 1

分析：令

3	a

=x，

3	b

=y，然后利用根式和分数指数幂的互化进行化简运算．

解答：解：令

3	a

=x，

3	b

=y
则原式=

x2+3xy+9y2

x4-27xy3

÷

x

x-3y

-

1

x2

=

x2+3xy+9y2

x(x3-27y3)

×

x-3y

x

-

1

x2

=0．

点评：本题考查根式和分数指数幂的化简运算，解题时要注意计算能力的培养．