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    The equation (x+1)3−(x−1)3=0(x+1)^3-(x-1)^3=0 (x+1)3−(x−1)3=0 is :
    Question

    The equation (x+1)3(x1)3=0(x+1)^3-(x-1)^3=0  is :

    A.

    ​a linear equation with real roots

    B.

    ​a quadratic equation with real roots

    C.

    ​a quadratic equation with non-real roots

    D.

    ​a linear equation with non-real roots

    Correct option is C

    Given:

    (x+1)3(x1)3=0(x+1)^3 - (x-1)^3 = 0  

    Formula used:

    (a+b)3=a3+3a2b+3ab2+b3(a + b)^3 = a^3 + 3a^2b + 3ab^2 + b^3 

    (ab)3=a33a2b+3ab2b3(a - b)^3 = a^3 - 3a^2b + 3ab^2 - b^3​​

    Solution: 

    ​ (x+1)3(x1)3=0(x+1)^3 - (x-1)^3 = 0​​

    (x+1)3(x1)3=0 (x3+3x2+3x+1)(x33x2+3x1)=0(x+1)^3 - (x-1)^3 =0 \\ \ \\(x^3 + 3x^2 + 3x + 1) - (x^3 - 3x^2 + 3x - 1) = 0​ 

    x3+3x2+3x+1x3+3x23x+1=0x^3 + 3x^2 + 3x + 1 - x^3 + 3x^2 - 3x + 1 = 0 

    6x2+2=06x^2 + 2 = 0 

    6x2=26x^2 = -2 

    x2=13x^2 = -\frac{1}{3} 

    x=±13x = \pm \sqrt{-\frac{1}{3}} 

    Since the solutions involve the imaginary unit , the roots are non-real.

    The correct answer is Option C :  quadratic equation with non-real roots.



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