\[\boxed{\mathbf{36.}}\]
\[\textbf{а)}\ y = 7x + a;\]
\[f^{'}(x) = 7;\]
\[y = x^{4} + 3x;\]
\[f^{'}(x) = 4x^{3} + 3.\]
\[Угловой\ коффициент\ \]
\[касательной:\]
\[4x^{3} + 3 = 7\]
\[4x^{3} = 4\]
\[x^{3} = 1\]
\[x = 1.\]
\[y_{0} = 1^{4} + 3 \cdot 1 = 1 + 3 = 4.\]
\[Уравнение\ касательной:\]
\[y - 4 = 7(x - 1)\]
\[y - 4 = 7x - 7\]
\[y = 7x - 3.\]
\[Найдем\ значение\ a:\]
\[a = - 3.\]
\[Ответ:a = - 3.\]
\[\textbf{б)}\ y = - 10x + a;\]
\[f^{'}(x) = - 10;\]
\[y = x^{6} - 4x;\]
\[f^{'}(x) = 6x^{5} - 4.\ \]
\[Угловой\ коэффициент\ \]
\[касательной:\]
\[6x^{5} - 4 = - 10\]
\[6x^{5} = - 6\]
\[x^{5} = - 1\]
\[x = - 1;\]
\[y_{0} = ( - 1)^{5} - 4 \cdot ( - 1) = 5.\]
\[Уравнение\ касательной:\]
\[y - 5 = - 10(x + 1)\]
\[y - 5 = - 10x - 10\]
\[y = - 10x - 5.\]
\[Значение\ a:\]
\[a = - 5.\]
\[Ответ:a = - 5.\]