\[\boxed{\text{611\ (611).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[(6x - a)^{2} + (8x - 3)^{2} =\]
\[= (10x - 3)^{2}\]
\[36x^{2} - 12\text{ax} + a^{2} + 64x^{2} - 48x + 9 =\]
\[= 100x^{2} - 60x + 9\]
\[- 12ax + a^{2} - 48x + 9 + 60x - 9 =\]
\[= 0\]
\[12x - 12ax + a^{2} = 0\]
\[12x \cdot (1 - a) + a^{2} = 0\]
\[при\ a = 1:\ \ \]
\[12x \cdot (1 - 1) + 1^{2} = 0\]
\[12x \cdot 0 + 1 = 0\]
\[0x \neq - 1\]
\[нет\ корней.\]
\[Ответ:при\ a = 1.\]