Question

tính tổng 

B=1+5+5^2+5^3 + ...5^50

Answer 1

B=1+5+5^2+5^3 + ...5^50

=> 5B=5+5^2+5^3+...+5^51=> 5B-B=4B=(5+5^2+5^3+...+5^51)-(1+5+5^2+5^3 + ...5^50)=> 4B=5^51-1=> B=\(\frac{5^{51}-1}{4}\)

Answer 2

\(B=1+5+5^2+5^3+...+5^{50}\)

\(\Rightarrow5B=5+5^2+5^3+...+5^{51}\)

\(\Rightarrow5B-B=\left(5+5^2+5^3+...+5^{51}\right)-\left(1+5+5^2+...+5^{50}\right)\)

\(\Rightarrow4B=5^{51}-1\)

\(\Rightarrow B=\frac{5^{51}-1}{4}\)

Answer 3

\(B=1+5+5^2+5^3+...+5^{50}\)
\(\Rightarrow5B=5+5^2+5^3+...+5^{50}\)
\(\Rightarrow5B-B=4B=\left(5+5^2+5^3+...+5^{51}\right)-\left(1+5+5^2+5^3+...+5^{50}\right)\)
\(\Rightarrow4B=5^{51}-1\)
\(\Rightarrow B=\frac{5^{51}-1}{4}\)
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