Question

nhanh giup mik v a 

Answer 1

\(\dfrac{1}{2}\cdot2^n+4\cdot2^n=9\cdot5^n\)

=>\(\dfrac{9}{2}\cdot2^n=9\cdot5^n\)

=>\(2^n=9\cdot5^n:\dfrac{9}{2}=2\cdot5^n\)

=>\(\left(\dfrac{2}{5}\right)^n=2\)

=>\(n=log_{\dfrac{2}{5}}2\)

Answer 2

a) \(\dfrac{1}{2}.2^n+4.2^n=9.5^n\)

\(\left(\dfrac{1}{2}+4\right).2^n=9.5^n\)

\(\dfrac{9}{2}.2^n=9.5^n\)

\(2^n=9.5^n:\dfrac{9}{2}\)

\(\left(\dfrac{2}{5}\right)^n=2\)

\(\Rightarrow\)Không có giá trị \(n\) thỏa mãn