一道分解因式的题目 运用公式法

1.49(a-b)²-16(a＋b)²
＝〔7(a-b)〕²-〔4(a＋b)〕²
＝〔7(a-b)＋4(a＋b)〕〔7(a-b)-4(a＋b)〕
＝(7a-7b＋4a＋4b)(7a-7b-4a-4b)
＝(11a-3b)(3a-11b)；
2.(2x+y)²-(x+2y)²
= (2x+y+x+2y)[2x+y-(x+2y)]
= (3x+3y)(x-y)
3.(x²+y²)²-x²y²
=(x²+y²)²-(xy)²
=(x²+y²+xy)(x²+y²-xy)
4.3ax²-3ay的四次方
=3a(x²-x的四次方;)
=3a(x+x²)(x-x²)
5.p的四次方-1
=(p²+1)(p²-1)
=(p²+1)(p+1)(p-1)
写了那么多,分可以给我了吧^_^