急~有數學唔識做？？

ax+2ay+bx+2by
=ax+bx+2ay+2by
=x(a+b)+2y(a+b)
=(x+2y)(a+b)

(a+b)2-(a-b)2
=[(a+b)-(a-b)][(a+b)+(a-b)]
=2b(2a)
=4ab


1.x2-9
=(x-3)(x+3)

2.ac+bc-ad-bd
=c(a+b)-d(a+b)
=(c-d)(a+b)

3.x2-(y-z)2
=[x-(y-z)][x+(y-z)]
=(x-y+z)(x+y-z)