Ta có:

\(\frac{2}{-7}=\frac{-2}{7}=\frac{-22}{77}\)

\(\frac{-3}{11}=\frac{-21}{77}\)

Vì -22 < -21 nên \(\frac{-22}{77}< \frac{-21}{71}\) hay x < y

\(x=-\frac{2}{7}=-\frac{2\cdot11}{7\cdot11}=-\frac{22}{77}\)

\(y=-\frac{3}{11}=-\frac{3\cdot7}{11\cdot7}=-\frac{21}{77}\)

Vì \(-\frac{21}{77}>-\frac{22}{77}\)

\(\Leftrightarrow y>x\)

vi 2/7 >0

mà -3/11<0

suy ra 2/7>0>-3/11

mk trước nha bạn 

Ta có:\(x=\frac{2}{-7}=\frac{-2}{7}=\frac{-22}{77}\)

           \(y=\frac{-3}{11}=\frac{-21}{77}\)

Mà \(\frac{-22}{77}< \frac{-21}{77}\)nên\(x< y\)

2⁷    >    7²

2^7  >   7^2 nha bạn

\(7\times2^{13}<2^3\times2^{13}=8\times2^{13}\)

cam on may ban da giup do

so sanh A = a*b /a^2+b^2 va B =  a^2+b^2/(a+b)^2

11/18.

5/8

5/13.

Chúc bạn may mắn nhé!

Ta có : 

\(2^{70}=\left(2^7\right)^{10}=128^{10}\)

\(7^{20}=\left(7^2\right)^{10}=49^{10}\)

Vì 128 > 49 nên \(128^{10}>49^{10}\)

Vậy \(2^{70}>7^{20}\) .

\(2^{70}=14^{10}\)

\(7^{20}=7^{10}.7^{10}\)

\(\Rightarrow2^{70}>7^{20}\)

\(2^{70}=2^{7.10}=\left(2^7\right)^{10}=128^{10}\)

\(7^{20}=7^{2.10}=\left(7^2\right)^{10}=49^{10}\)

\(128>49\Rightarrow128^{10}>49^{10}\Rightarrow2^{70}>7^{20}\)