Given equation, x4−2x3−12x2+10x+3=0
Consider f(x)=x4−2x3−12x2+10x+3
By inspection we can easily see that f(1)=0. Therefore, (x−1) is one factor of the given equation
∴f(x)=(x−1)⋅g(x)⟹g(x)=x3−x2−13x−3
We need to find root of g(x)=0
⟹x3−x2−13x−3=0⟹x3+3x2−4x2−12x−x−3=0⟹(x+3)(x2−4x−1)=0
Solving the quadratic equations, we have x=2±√5
∴ The roots of the given equation are x=1,−3,2±√5