\[\begin{array}{l}
1)\,\,{105^2} - 25 = {105^2} - {5^2} = \left( {105 - 5} \right)\left( {105 + 5} \right) = 100.110 = 11000.\\
2)\,\,{73^2} - {27^2} = \left( {73 - 27} \right)\left( {73 + 27} \right) = 46.100 = 4600.\\
3)\,\,{37^2} - {13^2} = \left( {37 - 13} \right)\left( {37 + 13} \right) = 24.50 = 1200.\\
4)\,\,{200^2} - {2^2} = 40000 - 4 = 39996.\\
5)\,\,\,\,{37^2} + 2.37.13 + {13^2} = {\left( {37 + 13} \right)^2} = {50^2} = 2500\\
6)\,\,\,{127^2} + 146.127 + {73^2}\\
= {127^2} + 2.127.73 + {73^2} = {\left( {127 + 73} \right)^2} = {200^2} = 40000.
\end{array}\]
