Question

Cho a = 2 + 2 mu 2 + 2 mu 3 +.....+ 2 mu 100

tính 2.a

tìm x biết 

2.a -a=2 mu x -2

Answer 1

bn có thể viết cả mũ ra hay ko

Answer 2

\(2a=2.\left(2+2^2+...+2^{100}\right)\)

\(2a=2^2+2^3+...+2^{101}\)

\(2a-a=\left(2^2+2^3+...+2^{101}\right)-\left(2^1+2^2+...+2^{100}\right)\)

\(2a-a=2^{101}-2\)

mà \(2a-a=2^x-2=>x=101\)

Answer 3

101 nha

Answer 4

\(a=2+2^2+2^3+...+2^{100}\)

\(\Rightarrow2a=2^2+2^3+2^4+....+2^{101}\)

\(2a-a=\left(2^2+2^3+2^4+...+2^{101}\right)-\left(2+2^2+2^3+...+2^{100}\right)\)

\(a=2^{101}-2\)

\(\Rightarrow2a=2\left(2^{101}-2\right)\)

\(2a-a=2^x-2\)

\(\Leftrightarrow2^x-2=2^{101}-2\)

\(\Leftrightarrow x=101\)

Answer 5

ta có: A = 2 + 2² + 2³ + ...+ 2¹⁰⁰

=> 2A = 2² + 2³ + 2⁴ +...+2¹⁰¹

Tìm x:

2.a - a = 2^x-2

a.(2-1) = 2^x-2

a = 2^x-2