急需！跪求極限值QQ...?

(題目印漏了Δ)
lim(Δx→0) ((x+Δx)² - 2(x+Δx) + 1 - (x²-2x+1))/Δx
= lim(Δx→0) ((x+Δx -1)² - (x-1)²)/Δx
= lim(Δx→0) (x+Δx -1 - (x-1))(x+Δx -1 + x-1)/Δx
= lim(Δx→0) Δx (2x+Δx -2)/Δx
= lim(Δx→0) (2x+Δx -2)
= 2x+0 -2
= 2x-2