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    Both the roots of the equation (x − a)(x − b) + (x − b)(x − c) + (x − c)(x − a) = 0 are always:
    Question

    Both the roots of the equation (x − a)(x − b) + (x − b)(x − c) + (x − c)(x − a) = 0 are always:

    A.

    Positive 

    B.

    Negative 

    C.

    Real 

    D.

    Zero

    Correct option is C

    Given:

    Equation: (x − a)(x − b) + (x − b)(x − c) + (x − c)(x − a) = 0

    Solution:
    Expand each term:

    (x − a)(x − b) = x² − (a + b)x + ab
    (x − b)(x − c) = x² − (b + c)x + bc
    (x − c)(x − a) = x² − (c + a)x + ca

    Adding all:
    3x² − 2(a + b + c)x + (ab + bc + ca) = 0

    This is a quadratic in x.

    Discriminant,
    D = [−2(a + b + c)]² − 4(3)(ab + bc + ca)
    = 4[(a + b + c)² − 3(ab + bc + ca)]
    = 4[a² + b² + c² − ab − bc − ca]
    = 2[(a − b)² + (b − c)² + (c − a)²] ≥ 0

    Hence D ≥ 0 for all real a, b, c.

    So, both roots are always real.

    Correct answer is (c) Real.

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