Question

giúp mk với: tính

M=1+3+3 mũ 2+3mũ 3+...+3mũ 25

Answer 1

Ta có: M = 1 + 3  + 3² + 3³ + ... + 3²⁵

=> 3M = 3(1 + 3 +3² + 3³ + ... + 3²⁵)

=> 3M = 3 + 3² + 3³ + ... + 3²⁵ + 3²⁶

=> 3M - M = (3 + 3² + 3³ + ... + 3²⁶) - (1 + 3 + 3² + 3³ + ... + 3²⁵)

=> 2M = 3²⁶ - 1

=> M = \(\frac{3^{26}-1}{2}\)

Answer 2

^ là mũ nha

M=1+3+3^2+3^3+....+3^25

3M=3+3^2+3^3+3^4+...+3^26

=>2M=3M-M=3^26-1

=>M=2M:2=(3^26-1):2

Vậy M=(3^26-1):2

Answer 3

M=1+3+3²+3³+......+3²⁵

3M=3(1+3+3²+3³+......+3²⁵)

3M=3+3²+3³+......+3²⁵+3²⁶

3M-M=(3+3²+3³+......+3²⁵+3²⁶) - (1+3+3²+3³+......+3²⁵)

Suy ra:M= (3²⁶ - 1) : 2

Answer 4

Đặt \(A=1+3+3^2+...+3^{25}\)

\(\Rightarrow3A=3+3^2+3^3+..+3^{26}\)

\(\Rightarrow2A=3^{26}-1\)

\(\Rightarrow A=\frac{3^{26}-1}{2}\)

Answer 5

\(M=1+3+3^2+3^3+...+3^{25}\)

\(\Rightarrow3M=3+3^2+3^3+3^4+...+3^{26}\)

\(\Rightarrow3M-M=\left(3+3^2+...+3^{26}\right)-\left(1+3+...+3^{25}\right)\)

\(\Rightarrow2M=3^{26}-1\Rightarrow M=\frac{3^{26}-1}{2}\)