3x-3y+x²+2xy+y² Tính giúp mình với!

$\displaystyle  \begin{array}{{>{\displaystyle}l}}
a)\sqrt{64} =\sqrt{8^{2}} =8\\
\Rightarrow 8=\sqrt{64}\\
b) 13=\sqrt{13^{2}} =\sqrt{169}\\
có:\ 169< 170\\
\Rightarrow \sqrt{169} < \sqrt{170}\\
\Rightarrow 13< \sqrt{170}\\
c) 15=\sqrt{15^{2}} =\sqrt{225}\\
có:\ 225< 227\\
\Rightarrow \sqrt{225} < \sqrt{227}\\
\Rightarrow 15< \sqrt{227}\\
d) 7=\sqrt{7^{2}} =\sqrt{49}\\
có:\ 48< 49\\
\Rightarrow \sqrt{48} < \sqrt{49}\\
\Rightarrow \sqrt{48} < 7\\
\Rightarrow -\sqrt{48}  >-7\\
e) 11=\sqrt{11^{2}} =\sqrt{121}\\
có:\ 120< 121\\
\Rightarrow \sqrt{120} < \sqrt{121}\\
\Rightarrow \sqrt{120} < 11\\
\Rightarrow -\sqrt{120}  >-11
\end{array}$