lim(x→1)[1/(x-1)-3/(1-x^3)] (通分)
=lim(x→1)[(x^2+x+1)-3]/(1-x^3)
=lim(x→1)[x^2+x-2]/(1-x^3)
=lim(x→1)(x+2)(x-1)/[(x-1)(x^2+x+1)]
=lim(x→1)(x+2)/(x^2+x+1) (直接代入)
=1
答案是1
lim(x→1)[1/(x-1)-3/(1-x^3)] (通分)
=lim(x→1)[(x^2+x+1)-3]/(1-x^3)
=lim(x→1)[x^2+x-2]/(1-x^3)
=lim(x→1)(x+2)(x-1)/[(x-1)(x^2+x+1)]
=lim(x→1)(x+2)/(x^2+x+1) (直接代入)
=1
答案是1