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SSC CGL 2021 PYQ — Question 65

SSC CGL - 23 Aug 2021 - Shift 2 • Quantitative Aptitude • Q65

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If (x + 6)3 + (2x + 3)3 + (3x + 5)3 = (3x +18)(2x + 3)(3x + 5), then what is the value of x?

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Correct answer: C

Explanation

The correct answer is option 3 i.e.  - 73\frac{7}{3}

Here it is given that,

⇒ (x + 6)3 + (2x + 3)3 + (3x + 5)3 = (3x +18)(2x + 3)(3x + 5)

⇒ (x + 6)3 + (2x + 3)3 + (3x + 5)3 = 3(x + 6)(2x + 3)(3x + 5)

⇒ (x + 6)3 + (2x + 3)3 + (3x + 5)3 - 3(x + 6)(2x + 3)(3x + 5) = 0

We know that, a3 + b3 + c3 -3abc = 0 only when a + b + c = 0.

⇒ x + 6 + 2x + 3 + 3x + 5 = 0

6x + 14 = 0

x = -7/3.