If (a+ib)(c +id)(e + if)(g + ih) = A + iB , then ( a2+b2)(c2+d2)(e2+f2)(g2+h2) =
A2 - B2
A2 + B2
A4 + B4
A4 - B4
|(a+ib)(c+id)(e+if)(g+ih)|2=|A+iB|2
∴ (a2+b2)(c2+d2)(e2+f2)(g2+h2)=A2+B2
If (a + ib) (c + id) (e + if) (g + ih) = A + iB, then show that
(a2 + b2) (c2 + d2) (e2 + f2) (g2 + h2) = A2 + B2.