16（a+b)²-9(a-b)²
=[4(a+b)+3(a-b)][4(a+b)-3(a-b)]
=(4a+4b+3a-3b)(4a+4b-3a+3b)
=(7a+b)(a+7b)9(x-3)²-4(2-3x)²-4(x-y)²＋16z²9(x-3)²-4(2-3x)² =[3(x-3)+2(2-3x)][3(x-3)-2(2-3x)]=(3x-9+4-6x)(3x-9-4+6x)=(-3x-5)(9x-13)=-(3x+5)(9x-13) -4(x-y)²＋16z²=[4z-2(x-y)][4z+2(x-y)]=(4z-2x+2y)(4z+2x-2y)=4(2z-x+y)(2z+x-y)再麻煩一下，我真心做不來(lái)。169x²-196y²(2x+y)²-(x+2y)²169x²-196y²=(13x+14y)(13x-14y) (2x+y)²-(x+2y)²=(2x+y+x+2y)(2x+y-x-2y)=(3x+3y)(x-y)=3(x+y)(x-y)