Question

A= 1+5+5^2+....+5^50

Answer 1

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

\(\Rightarrow5A=5+5^2+5^3+...+5^{51}\)

\(5A-A=4A=5^{51}-1\)

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

Vậy \(A=\frac{5^{51}-1}{4}\)

Answer 2

A = 1 + 5 + 5² + ... + 5⁵⁰

5A = 5 + 5² + 5³ + ... + 5⁵¹

5A - A = (5 + 5² + 5³ + ... + 5⁵¹) - (1 + 5 + 5² + ... + 5⁵⁰)

4A = 5⁵¹ - 1

A = 5⁵¹ - 1/4

Ủng hộ mk nha ^_-