Question

Tìm A biết:

A= 4+2^2+2^3+...+2^18

 

Answer 1

A = 4 + 2^2 + 2^3 + ... + 2^18

A = 524288

Answer 2

 4 + 2² + 2³ + .... + 2¹⁸

= 2² + 2² + 2³ +... + 2¹⁸ 

= 2³ + 2³ +... + 2¹⁸ 

=   2⁴ +  ...   + 2¹⁸ 

= ..... 2¹⁸ + 2¹⁸

= 2¹⁹ = 524288

vậy A = 524288

Answer 3

A=4+2^2+2^3+...+2^18

2A=2^3+2^3+2^4+...+2^19

2A-A=2^3+2^3+2^4+...+2^19-2^2-2^2-2^3-...-2^18

A=2^3-2^2-2^2+2^19

A=524288