Question

Answer 1

Bài 6:
a)\(S=1+2+2^2+...+2^{10}\)
\(\Leftrightarrow2S=2+2^2+2^3+...+2^{11}\)
\(\Rightarrow2S-S=\left(2+2^2+2^3+...+2^{11}\right)-\left(1+2+2^2+...+2^{10}\right)=2^{11}+1\)
\(\Rightarrow S=\dfrac{2^{11}+1}{2}\)

Answer 2

Bài 7:
a)\(2^{30}=\left(2^3\right)^{10}=8^{10}\)      \(3^{20}=\left(3^2\right)^{10}=9^{10}\)
\(\Rightarrow2^{30}< 3^{20}\)
b)\(10^{20}=\left(10^2\right)^{10}=100^{10}\)     \(\Rightarrow10^{20}>20^{10}\)