6.a≥ 1/2

7.(3x+ 1)(9x+3)

8.4 x^6 y^8

9.(x+y+2)(x+y-2)

10.2

1 1. solution: original formula =mn(m? +2mn+n？ )

=mn(m+n)？

=2/3*3?

=6

14.-3x？ y？

15. Solution: Original formula =2x? -Really? -2xy+8x？ +y？ -4xy+6xy

= 10x？

= 10*-2?

=40

So Xiao Xin was right.

It's over. The story about me has been written for a long time. I hope it can be adopted.