Toán Tìm giới hạn : lim x->1 (x+x^2+…+x^n – n)/(x+1) 08/07/2021 By Melody Tìm giới hạn : lim x->1 (x+x^2+…+x^n – n)/(x+1)
$\lim_{x \to 1} (x+x^2+…+x^n-$ $\frac{n}{1-x})$ $=\lim_{x \to 1} \frac{x(1-x^n)-n}{1-x}$ $=\frac{\lim_{x \to 1}[x(1-x^n)-n]}{\lim_{x \to 1}(1-x)}=-∞$ Trả lời
Lời giải: $lim_{x→1}\frac{x+x^2+…+x^n-n}{x+1}=\frac{1+1+…+1-n}{2}=\frac{n-n}{2}=\frac{0}{2}=0$ Trả lời
$\lim_{x \to 1} (x+x^2+…+x^n-$ $\frac{n}{1-x})$
$=\lim_{x \to 1} \frac{x(1-x^n)-n}{1-x}$
$=\frac{\lim_{x \to 1}[x(1-x^n)-n]}{\lim_{x \to 1}(1-x)}=-∞$
Lời giải:
$lim_{x→1}\frac{x+x^2+…+x^n-n}{x+1}=\frac{1+1+…+1-n}{2}=\frac{n-n}{2}=\frac{0}{2}=0$