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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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