Question

Bài 1 :Cho a = 2 mũ 1 +2 mũ 2 + 2 mũ 3 +.... + 2 mũ 100 .Tìm x  thuộc N sao cho a+2=2 mũ x

 

Bài 2 : Có hay không 3 số tự nhiên lẻ a,b,c thỏa mãn a mũ 2 + b mũ 2 - c mũ 2 = 2016

 

      CẢM ƠN CÁC BẠN ĐÃ TRẢ LỜI .  THANK YOU SO MUCH<3 

Answer 1

\(a=2^1+2^2+2^3+...+2^{100}\)

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

\(2a-a=\left(2^2+2^3+2^4+...+2^{101}\right)-\left(2^1+2^2+2^3+...+2^{100}\right)\)

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

\(a+2=2^{101}-2+2=2^{201}\)

\(\Rightarrow x=101\)

Answer 2

\(a=2^1+2^2+2^3+...+2^{100}\)

\(2a=2^2+2^3+2^4+...+2^{99}+2^{100}\)

\(2a-a=\left(2^2+2^3+2^4+...+2^{99}+2^{100}\right)-\left(2^1+2^2+2^3+...+2^{100}\right)\)

\(a=2^{99}-2\)

\(a+2=2^{99}-2+2=2^{99}\)

\(\Rightarrow x=99\)

Answer 3

\(a=2^1+2^2+2^3+...+2^{100}\)

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

\(2a-a=2^2+2^3+...+2^{100}+2^{101}-2-2^2-2^3-...-2^{99}-2^{100}\)

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