x2 (a2 + b2) + 2x(ac + bd) + (c2 + d2) = 0
The equation will have no real roots only if Discriminant(D) < 0
⇒ b2 – 4ac < 0
⇒ b2 – 4ac
⇒ [2(ac + bd)]2 – 4 (a2 + b2) (c2 + d2)
⇒ 4(ac + bd)2 – 4(a2c2 + a2d2 + b2c2 + b2d2)
⇒ 4(a2c2 + b2d2 + 2abcd) – 4(a2c2 + a2d2 + b2c2 + b2d2)
⇒ 4a2c2 + 4b2d2 + 8abcd – 4a2c2 – 4a2d2 – 4b2c2 – 4b2d2
⇒ – 4a2d2 – 4b2c2 + 8abcd
– 4 [a2d2 + b2c2 – 2abcd]
– 4[(ad – bc)2]
For ad ≠ bc
D = – 4 × [Value of (ad – bc)2]
∴ D always remain negative
So, D < 0
⇒ The given equation has no real roots.