证明:lim(x→∞)[(3x^2-x)(x^2+10)]
=lim(x→∞)[3(x^2+10)-30-x]/(x^2+10)
=lim(x→∞)[3-30/(x^2+10)-1/(x+10/x)
=lim(x→∞)[3-0-0]
=limx(→∞)(3)
=3.
证明:lim(x→∞)[(3x^2-x)(x^2+10)]
=lim(x→∞)[3(x^2+10)-30-x]/(x^2+10)
=lim(x→∞)[3-30/(x^2+10)-1/(x+10/x)
=lim(x→∞)[3-0-0]
=limx(→∞)(3)
=3.