.=x²-(x²-4)-(x+1/2)²=4-(x+1/2)²=(2+x+1/2)(2-x-1/2)=(x+5/2)(3/2-x)
.=999×999+999×2+1=(999+1)²=10000000
.=(x+y+1)²
.=[2(a-b)+4(a+b)][2(a-b)-4(a+b)]=(6a+2b)(-2a-6b)
.=-2b(a²-2a+1)=-2b(a-1)²
.=第六题有点不正常诶.看看题有没有打错啊,打错了追问一下.
.=(a²+1+2a)(a²+1-2a)=(a+1)²(a-1)²