A real value of x satisfies the equation 3−4ix3+4ix=a−b(a, bϵR), if a2+b2
1
Given equation,
(3−4ix3+4ix)=a−b(α, βϵR)⇒ [3−4ix3+4ix]=α−iβNow (x−iβ)=(3−4ix)(3−4ix)(3+4ix)(3−4ix)=9+16i2x2−24ix9−16i2x2⇒ α−iβ=9−16x2−24ix9+16x2⇒ α−iβ=9−16x29+16x2−i24x9+16x2 ...(i)∴ α+iβ=9−16x29+16x2+i24x9+16x2 ...(ii)So,(α−iβ)(α+iβ)=(9−16x29+16x2)2−(i24x9+16x2)2∴ α2+β2=81+256x4−288x2+576x2(9+16x2)2=81+256x4+288x2(9+16x2)2=(9+16x2)2(9+16x2)2=1