Đáp án:b)$\frac{1}{7}$
d)5
Giải thích các bước giải:
b)$lim\frac{4·3^{n}+7^{n-1}}{2·5^{n}+7^{n}}$
=$lim\frac{4·3^{n}+\frac{7^{n}}{7}}{2·5^{n}+7^{n}}$
=$lim\frac{7^{n}[4·(\frac{3}{7})^{n}+\frac{1}{7}]}{7^{n}[2·(\frac{5}{7})^{n}+1]}$
=$\frac{1}{7}$
d)$lim\frac{2^{n}+5^{n+1}}{1+5^{n}}$
=$lim\frac{2^{n}+5^{n}·5}{1+5^{n}}$
=$lim\frac{5^{n}[(\frac{2}{5})^{n}+5]}{5^{n}[(\frac{1}{5})^{n}+1]}$
=$5$
