Question

Решите уравнение a^3+7a^2-9a-63=0

Answer 1

$\displaystyle\bf\\a^{3}+7a^{2}-9a-63=0 \\\\(a^{3}+7a^{2})-(9a+63)=0 \\\\a^{2}\cdot(a+7)-9(a+7)=0\\\\(a+7)\cdot(a^{2} -9)=0\\\\(a+7)\cdot(a-3)\cdot(a+3)=0\\\\\\\left[\begin{array}{ccc}a+7=0\\a-3=0\\a+3=0\end{array}\right\\\\\\\left[\begin{array}{ccc}a_{1}=-7\\a_{2} =3\\a_{3} =-3\end{array}\right\\\\\\Otvet \ : \ -7 \ ; \ 3 \ ; \ -3$