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SSC CGL 2024 PYQ — Question 61

SSC CGL - 11 Sep 2024 - Shift 3 • Quantitative Aptitude • Q61

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If x+19xx+\frac{1}{9x} = 3, then the value of 9x2+19x29x^2+\frac{1}{9x^2} is:

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Correct answer: D

Explanation

The correct answer is option 4 i.e. 79.

x + 1/9x = 3    

Multiplying both sides by 3 

⇒ (3x + 1/3x) = 9

⇒ (3x + 1/3x)2 = 92 

⇒ 9x2 + 1/9x2 = 81 - 2

⇒ 9x2 + 1/9x2 = 79