Question

tính c= \(4+4^2+4^3+...+4^n\)

 mình cần rất gấp lun mn ui giúp vs

 

Answer 1

\(\Rightarrow4C=4^2+4^3+...+4^{n+1}\)

\(\Rightarrow4C-C=\left(4^2+4^3+...+4^{n+1}\right)-\left(4+4^2+...+4^n\right)\)

\(\Rightarrow3C=4^{n+1}-4\)

\(\Rightarrow C=\frac{4^{n+1}-4}{3}\)

Answer 2

\(4C=4^2+4^3+4^4+...+4^{n+1}\)

\(4C-C=4^2+4^3+...+4^{n+1}-4-4^2-...-4^n\)

\(3C=4^{n+1}-4\)

\(C=\frac{4^{n+1}-4}{3}\)

Answer 3

\(C=4+4^2+4^3+....+4^n\)

\(4C=4^2+4^3+4^4+.....+4^{n+1}\)

\(3C=4^{n+1}-4\)

\(C=\frac{4^{n+1}-4}{3}\)

Answer 4

ta có \(c=4+4^2+4^3+...+4^n\)

\(\Rightarrow4c=4^2+4^3+4^4+...+4^{n+1}\)

\(\Rightarrow4c-c=3c=4^{n+1}-4\)

\(\Rightarrow c=\frac{4^{n+1}-4}{3}\)