Question

求极限limx→1（1/1-x²-1/1-x）=

Answer 1

limx 趋近于1(1/1-x²－1/1-x)化简等于lim x 趋近于1(-x＋1-1除于(1+x)(1-x))结果代入＝-1/2

Answer 2

lim (x²+x-2)/(x³-x²+x-1)
x→-1
=lim (x-1)(x+2)/[x²(x-1)+(x-1)]
x→-1
=lim (x-1)(x+2)/[(x-1)(x²+1)]
x→-1
=lim (x+2)/(x²+1)
x→-1
=(-1+2)/[(-1)²+1]
=½
lim (x²+x-2)/(x³-x²+x-1)
x→1
=lim (x-1)(x+2)/[x²(x-1)+(x-1)]
x→1
=lim (x-1)(x+2)/[(x-1)(x²+1)]
x→1
=lim (x+2)/(x²+1)
x→1
=(1+2)/(1²+1)
=3/2