Question

Помогите решить уравнение: x^3+3x^2+5x-15=0

30 баллов

Answer 1

$x^{3}+3x^{2}-5x-15=0\\\\(x^{3}+3x^{2})-(5x+15)=0\\\\x^{2}(x+3)-5(x+3)=0\\\\(x+3)(x^{2}-5)=0\\\\(x+3)(x-\sqrt{5})(x+\sqrt{5} )=0\\\\\\\left[\begin{array}{ccc}x+3=0\\x-\sqrt{5} =0\\x+\sqrt{5}=0 \end{array}\right\\\\\\\left[\begin{array}{ccc}x_{1}=-3 \\x_{2}=\sqrt{5}\\x_{3}=-\sqrt{5} \end{array}\right$