Question

E = 1 + 2¹ + 2⁴ + 2⁷ + 2¹⁰ + ......... + 2²⁰¹⁷

Answer 1

Ta có : E= \(1+2^1+2^4+2^7+2^{10}+....+2^{2017}\)

\(\Rightarrow\) \(2^3\) . E =\(2^3.\)( \(1+2^1+2^4+2^7+2^{10}+....+2^{2017}\))

\(\Rightarrow8E=\)\(2^3+2^4+2^7+2^{10}+2^{13}+....2^{2017}+2^{2020}\)

\(\Rightarrow8E-E=\)\(2^3+2^4+2^7+2^{10}+2^{13}+....2^{2017}+2^{2020}\)\(-\)

(\(1+2^1+2^4+2^7+2^{10}+....+2^{2017}\))

\(\Rightarrow\)7E=\(2^3+2^{2020}-\left(1+2^1\right)\)

\(\Rightarrow7E=2^3+2^{2020}-3\)

\(\Rightarrow7E=5+2^{2020}\)

\(\Rightarrow E=\left(5+2^{2020}\right):7\)

Chỉ viết về dạng đó thui bạn nhé :))

Answer 2

E = 1 + 2¹ + 2⁴ + 2⁷ + 2¹⁰ + ......+ 2²⁰¹⁷

2E = 2¹ + 2⁴ + 2⁷ + 2¹⁰ + .........+2²⁰²⁰

2E - E = 2²⁰²⁰ - 1

1 = 2²⁰²⁰ - 1

E = 2²⁰²⁰ - 1/1

/ là phần nha mình ko viết được nha sorry

like nha