2^8 . 4^5 . 9^9

=2^8 . (2^2)^5 . (3^2)^9

=2^8 . 2^10 . 3^18

=2^18 . 3^18

=(3.2)^18

=6^18

\(2^8.4^5.9^9=2^8.\left(2^2\right)^5.\left(3^2\right)^9\)\(=2^8.2^{10}.3^{18}\)\(=2^{18}.3^{18}\)

\(A=1+3+3^2+3^3+3^4+...+3^{2015}\)

\(=\left(1+3+3^2+3^3\right)+\left(3^4+3^5+3^6+3^7\right)+...+\left(3^{2012}+3^{2013}+3^{2014}+3^{2015}\right)\)

\(=\left(1+3+3^2+3^3\right)+3^4\left(1+3+3^2+3^3\right)+...+3^{2012}\left(1+3+3^2+3^3\right)\)

\(=\left(1+3+3^2+3^3\right)\left(1+3^4+...+3^{2012}\right)\)

\(=40\left(1+3^4+...+3^{2012}\right)\)\(⋮\)\(5\)

\(B=2+2^2+2^3+...+2^{2016}\)

\(=\left(2+2^2+2^3+2^4\right)+\left(2^5+2^6+2^7+2^8\right)+...+\left(2^{2013}+2^{2014}+2^{2015}+2^{2016}\right)\)

\(=2\left(1+2+2^2+2^3\right)+2^5\left(1+2+2^2+2^3\right)+..+2^{2013}\left(1+2+2^2+2^3\right)\)

\(=\left(1+2+2^2+2^3\right)\left(2+2^5+...+2^{2013}\right)\)

\(=15\left(2+2^5+...+2^{2013}\right)\)\(⋮\)\(15\)

\(a>b\)Vì :\(7256.4375>3650+4375\)

I don't now

mik ko biết 

sorry 

......................

1)\(4n+3⋮n-2\)

\(\Leftrightarrow4n+3=4\left(n-2\right)+11\)

\(\Rightarrow4\left(n-2\right)⋮n-2\)\(\Rightarrow n-2⋮n-2\)

\(\Rightarrow11⋮n-2\)

\(\Rightarrow n-2\in\left\{\pm1;\pm11\right\}\)

\(\Rightarrow n\in\left\{3;1;13;-9\right\}\)

2)\(xy+5x+y+10=0\)

\(\Leftrightarrow x\left(y+5\right)+y+5+5=0\)

\(\Leftrightarrow x\left(y+5\right)+\left(y+5\right)=-5\)

\(\Leftrightarrow\left(x+1\right).\left(y+5\right)=-5\)

3)

I don't now

mik ko biết 

sorry 

......................