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SSC Selection Post 2019 PYQ — Question 70

SSC Selection Post - Graduation Level 2019 - 16 Oct 2019 • Quantitative Aptitude • Q70

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 If 9 + 2(3x - xy + x2) + y² = 0, then what is the value of (3x² - 2xy + 5y²)?
 

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Correct answer: B

Explanation

The correct answer is Option 2 i.e. 54.

9+2(3x−xy+x2)+y2=0⇒2x2−2xy+y2=−6x−99 + 2(3x - xy + x^2) + y^2 = 0 \Rightarrow 2x^2 - 2xy + y^2 = -6x - 9

3x2−2xy+5y2=(2x2−2xy+y2)+x2+4y2=−6x−9+x2+4y23x^2 - 2xy + 5y^2 = (2x^2 - 2xy + y^2) + x^2 + 4y^2 = -6x - 9 + x^2 + 4y^2

Let ( x = 3, y = 3 ):

−6(3)−9+32+4(32)=−18−9+9+36=54-6(3) - 9 + 3^2 + 4(3^2) = -18 - 9 + 9 + 36 = 54