Published by:
CGP EDU Academic Team
Published on: August 14, 2026
If f(x) = x 4 + ax 3 + bx 2 + cx + d be polynomial with real coefficient and real roots. If |f(i)| = 1, i = 
, then a + b + c + d is equal to
Text Solution
Verified by ExpertsThe correct answer is:
C
Let f(x) = (x – x 1 )(x – x 2 )(x – x 3 )(x – x 4 )
| f (i)| = 
= 1
⇒ x 1 = x 2 = x 3 = x 4 = 0
⇒ All four roots are zero ⇒ f(x) = x 4 ∴ a = b = c = d = 0
⇒ a + b + c + d = 0
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