\[\boxed{\text{1182\ (1182).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ 69^{2} = (70 - 1)^{2} =\]
\[= 4900 - 140 + 1 = 4761\]
\[2)\ 91^{2} = (90 + 1)^{2} =\]
\[= 8100 + 180 + 1 = 8281\]
\[3)\ 52^{2} = (50 + 2)^{2} =\]
\[= 2500 + 200 + 4 = 2704\]
\[4)\ 97^{2} = (100 - 3)^{2} =\]
\[= 10000 - 600 + 9 = 9409\]
\[5)\ 299^{2} = (300 - 1)^{2} =\]
\[= 90000 - 600 + 1 = 89\ 401\]
\[6)\ {10,2}^{2} = (10 + 0,2)^{2} =\]
\[= 100 + 4 + 0,04 = 104,04\ \ \]
\[\boxed{\text{1182.\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ A\ (12;\ - 4):\]
\[12a + 4 \cdot ( - 4) = 0\]
\[12a = 16\]
\[a = \frac{4}{3} = 1\frac{1}{3}\]
\[Ответ:при\ a = 1\frac{1}{3}.\]
\[2)\ B\ (0;2):\]
\[0 + 4 \cdot 2 = 0\]
\[8 \neq 0\ не\ проходит \Longrightarrow\]
\[\Longrightarrow a - не\ существует.\]
\[3)\ \text{O\ }(0;0):\]
\[0 + 0 = 0\ \]
\[0 = 0\ \]
\[при\ a - любое\ число.\]