Given equation, 2x4+x3−6x2+x+2=0
⟹2(x2+x−2)+(x+x−1)−6=0[dividing byx2]
Substitute x+x−1=y in the above equation
⟹2(y2−2)+y−6=0⟹2y2+y−6=0⟹(2y+5)(y−2)=0
⟹x+x−1=−52andx+x−1=2
Solving the 2 quadratic equations, we have 1,1,−2,−12 as the roots of the given equation