______(p+1)（P-3）+2(p-3)=(p-3)(p+3) 填那个下划线
因式分解
2X2-18B2
=2(x^2-9b^2)
=2(x+3b)(x-3b)
x^2y-1/2xy^2+1/16y^3
=y(x^2-1/2xy+1/16y^2)
=y(x-1/4y)^2