factorize

1. 9p²-q²-12p-4q
= (9p²-q²)-(12p+4q) 進行分類
= (3p+q)(3p-q)-4(3p-q) 有同類項
= (3p-q) (3p+q-4) 同類項抽出

2. x²y^4-16x²
= x²y^4-16x² 有同類項
= x²(y^4-16) 同類項抽出
= x²[(y^2)2-(4)2] a^2-b^2≡(a+b)(a-b)
= x²[(y^2+4) (y^2-4)]
= x²(y^2+4) [(y)^2-(2)^2] a^2-b^2≡(a+b)(a-b)
= x²(y^2+4)(y+2)(y-2)