1.x(x²-9)=x(x+3)(x-3)
2.(4x²+1)(4x²-1)=(4x²+1)(2x+1)(2x-1)
3.-y(9x²-6xy+y²)=-y(3x-y)²
4.第四题是不是错了,我按(2a-b)²+8ab=4a²+4ab+b²=(2a+b)²
1.x(x²-9)=x(x+3)(x-3)
2.(4x²+1)(4x²-1)=(4x²+1)(2x+1)(2x-1)
3.-y(9x²-6xy+y²)=-y(3x-y)²
4.第四题是不是错了,我按(2a-b)²+8ab=4a²+4ab+b²=(2a+b)²