Question

Tính tổng: \(B=5+5^2+5^3+...+5^{60}\)

Answer 1

5B = 5² + 5³ + 5⁴ + ... + 5⁶¹

5B - B = (5² + 5³ + 5⁴ + ... + 5⁶¹) - (5 + 5² + 5³ + ... + 5⁶⁰)

4B = 5⁶¹ - 5

\(B=\frac{5^{61}-5}{4}\)

Answer 2

Ta có: B = 5 + 5² + 5³ + ... + 5⁶⁰

=> 5B = 5² + 5³ + ... + 5⁶¹

=> 5B - B = 5⁶¹ - 5

=> 4B = 5⁶¹ - 5

=> B = \(\frac{5^{61}-5}{4}\)

Answer 3

\(B=5+5^2+5^3+..+5^{60}\) 

\(5B=5^2+5^3+5^4+...+5^{61}\)

\(5B-B=\left(5^2+5^3+5^4+...+5^{61}\right)-\left(5+5^2+5^3+..+5^{60}\right)\)

\(4B=5^{61}-5\)

\(B=\frac{5^{61}-5}{4}\)

Answer 4

Ta có:

      5B=5²+5³+5⁴+...+5⁶¹

-

       B=5+5²+5³+...+5⁶⁰

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=>4B=5⁶¹-5

=>B=(5⁶¹-5):4

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Answer 5

4B=(5²+5³+5⁴+...+5⁶¹)-(5+5²+5³+...+5⁶⁰⁾

4B=5⁶¹-5

B=\(\frac{5^{61}-5}{4}\)

Answer 6

\(B=5+5^2+5^3+.....+5^{60}\)

\(\Rightarrow5B=5^2+5^3+....+5^{61}\)

\(\Rightarrow5B-B=\left(5^2+5^3+....+5^{61}\right)-\left(5+5^2+5^3+.....+5^{60}\right)\)

\(\Rightarrow4B=5^{61}-5\)

\(\Rightarrow B=\frac{5^{61}-5}{4}\)

Answer 7

B=5+5²+5³+...+5⁶⁰

=>5B=5²+5³+5⁴+...+5⁶¹

=>5B-B=(5²+5³+5⁴+...+5⁶¹)-(5+5²+5³+...+5⁶⁰)

=>4B=5⁶¹-5

=>B=(5⁶¹-5):4

Answer 8

5B = 5² + 5³ + 5⁴ + ... + 5⁶¹

5B - B = (5² + 5³ + 5⁴ + ... + 5⁶¹) - (5 + 5² + 5³ + ... + 5⁶⁰)

4B = 5⁶¹ - 5

$B=\frac{5^{61}-5}{4}$