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Let f(x)=x^(3)+ax^(2)+bx+c be the given ...

Let `f(x)=x^(3)+ax^(2)+bx+c` be the given cubic polynomial and `f(x)=0` be the corresponding cubic equation, where `a, b, c in R.` Now, `f'(x)=3x^(2)+2ax+b`
Let `D=4a^(2)-12b=4(a^(2)-3b)` be the discriminant of the equation `f'(x)=0`.
IF `D=4(a^(2)-3b)lt0`. Then,

A

A) f(x) has all real roots

B

B) f(x) has one real and two imaginary roots

C

C) f(x) has repeated roots

D

D) None of the above

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