数学八年级下因式分解共6题,要过程,要答案,要正确,要快点!

(1)原式=b²-(a/2)²
=(b+a/2)(b-a/2)
(2)x²-81y²
=x²-(9y)²
=(x+9y)(x-9y)
(3)原式=3y(x²-9)
=3y(x²-3²)
=3y(x+3)(x-3)
(4)原式=（a²)²-1
=(a²+1)(a²-1)
=(a²+1)(a+1)(a-1)
(5)原式=x(x²-y²)
=x(x+y)(x-y)
(6)原式=[(2x+y)+(x+2y)][(2x+y)-(x+2y)]
=(2x+y+x+2y)(2x+y-x-2y)
=(3x+3y)(x-y)
=3(x+y)(x-y)