maths因式分解

1. (x-1)*2-(x+1)*2
= [ (x-1)+(x+1) ][ (x-1)-(x+1) ]
= 2x(-2)
= -4x

2. (25p*2-60p+36)-25y*2
= (5p-6)*2 - (5y)*2
= [5p-6-5y][5p-6+5y]

3.4p*4-16x*2y*2+q*4+4p*2q*2
= 4p*4 + 4p*2 q*2 + q*4 - 16x*2 y*2
= (2p*2 + q*2)*2 - (4xy)*2
= (2p*2+q*2-4xy)(2p*2+q*2+4xy)