=[(3x+2y)+(2x+3y)][(3x+2y)-(2x+3y)]
=(5x+5y)(x-y)
=5(x+y)(x-y)
(2)3x^3-12xy^2
=3x(x^2-4y^2)
=3x(x+2y)(x-2y)
(3)a^2b^2-4ab+4;
直接用完全平方
=(ab-2)^2
(4)a^2+16b^2+8ab
直接用完全平方
=(a+4b)^2
(5)1-x+1/4a^2
错了,应该是1-a+1/4a^2
直接用完全平方
=(1-1/2a)^2
(6)-4a^2x^2+12ax-9.
=-(4a^2x^2-12ax+9)
=-(2ax-3)^2