Question 856389
x^4+7x^3-8x-56=0
There should be four answers since x is to the 4th power. 
There are two real and two complex
(x+7) (x^3-8) = 0
(x+7)(x-2)(x^2+2x+4) = 0
x=2
x=-7 
x = -1-i sqrt(3)
x = -1+i sqrt(3)