SSC CGL 2022 PYQ — Question 62

SSC CGL - 18 April 2022 - Shift 2 • Quantitative Aptitude • Q62

If 22\sqrt{2}x3 - 33\sqrt{3}y3 = (2x−3y\sqrt{2x}-\sqrt{3y}) (Ax2 - Bxy +Cy2), then the value of \sqrt{}(A2 + B2 + C2) is:

Show answer & explanation

Correct answer: A

Explanation

The correct answer is option 1 i.e. 19\sqrt{19}.

x3 - y3 = (x - y)(x2 + xy + y2)

 22\sqrt{2}x3 - 33\sqrt{3}y3 = (2x−3y\sqrt{2x}-\sqrt{3y}) (Ax2 - Bxy +Cy2)

⇒ (2√2x3 - 3√3y3)/(√(2x) - √(3y)) = Ax2 - Bxy + Cy2

⇒ (2x−3y)(2x2+3y2−(6xy)2x−3y\frac{(\sqrt2x - \sqrt3y)(2x^2 + 3y^2 - (\sqrt6xy)}{\sqrt2x - \sqrt3y} = Ax2 - Bxy + Cy2

= (2x2 - √6xy + 3y2) = = Ax2 - Bxy + Cy2

On comparing with Ax2 - Bxy + Cy2 -

A = 2

B = √6

C = 3

⇒ √(A2 + B2 + C2) = √{22 + (√6)2 + 32} = √(4 + 6 + 9) = √19