应用洛必达法则求极限 :lim(x->1)[ ∫ (x到1)(t-1)lntdt ] /(x-1)²

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应用洛必达法则求极限 :lim(x->1)[ ∫ (x到1)(t-1)lntdt ] /(x-1)²
应用洛必达法则求极限 :lim(x->1)[ ∫ (x到1)(t-1)lntdt ] /(x-1)²

应用洛必达法则求极限 :lim(x->1)[ ∫ (x到1)(t-1)lntdt ] /(x-1)²
limit((int((t-1)*ln(t),t = x ..1))/(x-1)^2,x = 1)
=(-(1/2)*x^2*ln(x)+(1/4)*x^2+ln(x)*x-x+3/4)/(x-1)^2
=(-(1/2)*(`limit/X`+1)^2*ln(`limit/X`+1)+(1/4)*(`limit/X`+1)^2+ln(`limit/X`+1)*(`limit/X`+1)-`limit/X`-1/4)/`limit/X`^2
=0

变下限函数变成变上限函数,然后就是变上限函数求导,洛必达之后结果为(1-x)lnx/2(x-1)=0

用洛必达法则:注意:∫ (x到1)(t-1)lntdt=-∫ (1到x)(t-1)lntdt
=-lim(x-1)lnx/2(x-1)
=-limlnx/2
=0