Question

tìm \(lim\dfrac{1+2.3^n-7^n}{a+5^n+a.7^{n-1}}\)

Answer 1

\(\lim\dfrac{1+2.3^{n}-7^{n}}{a+5^{n}+a.7^{n-1}} =\lim\dfrac{(\dfrac{1}{7})^{n}+2.(\dfrac{3}{7})^{n}-1}{a.(\dfrac{1}{7})^{n}+(\dfrac{5}{7})^{n}+\dfrac{a}{7}} =\lim\dfrac{-1}{\dfrac{a}{7}} =\dfrac{-7}{a}\)