Question

[Ly]

b)cho A=2^0 +2^1+2^2+...+2^30

B= 2^31-1

So sanh A va B

c)cho A=2^0+2^1+2^2+...+2^100

Biết A+1=2^x.Tìm x

Answer 1

[I don't need you]

b) A  = 2⁰ +2¹ +2²+...+2³⁰

=> 2A = 2¹ +2²+2³+...+2³¹

=> 2A-A = 2³¹-2⁰

=> A = 2³¹ - 1 = B

c) A = 2⁰ +2¹+2²+...+2¹⁰⁰

=>2A = 2¹+2²+2³+...+2¹⁰¹

=> 2A-A = 2¹⁰¹-2⁰

A = 2¹⁰¹ - 1

=> A + 1 = 2¹⁰¹

mà A+ 1 = 2^x

=> x = 101