Question 691011
f(x)=x^3+4x^2-5x-20
set f(x) to zero and factor the right by grouping:
0=(x^3+4x^2)-(5x+20)
0=x^2(x+4)-5(x+4)
0=(x+4)(x^2-5)
x = {-4, {{{-sqrt(5)}}}, {{{sqrt(5)}}})