Question 1134043
x^4-6x^3+6x^2+24x-40=0  note: the 24 was edited to 24x
with synthetic division, -2 works
and the result is 1 -8 22 -20
so the factors are (x+2)(x^3-8x^2+22x-20)
with +2 and synthetic division, one sees (x-2)(x^2-6x+10), and the last is complex, with the roots x=(1/2)(6+/- sqrt (-4)) or 3+/-i
Roots are +/-2 and 3+/- i

{{{graph(300,300,-10,10,-10,10,x^4-6x^3+6x^2+24x-40)}}}