Since first equation is cubic,
roots will be -1, e±i2Π/3
substitute these roots in second equation and you'll see that the second equation satisfies at e±i2Π/3, hence the common roots
Find common roots of equation z3+2z2+2z+1=0 and z1985+z100+1=0
z3+2z2+2z+1=0
z3 + 1 + 2z2 + 2z
Hint: Now expand the first and second term
Since first equation is cubic,
roots will be -1, e±i2Π/3
substitute these roots in second equation and you'll see that the second equation satisfies at e±i2Π/3, hence the common roots
here 1,w ,w^2 are satisfied.
the roots are 1,w,w^2.
now w^3=1.
substitute in second
we get 0.