SSC Selection Post 2020 PYQ — Question 72

SSC Selection Post - Graduation Level 2020 - 10 Nov 2020 - Shift 3 • Quantitative Aptitude • Q72

If 8x6 - 66y66\sqrt{6}y^6 = (2x2 + Ay2)(4x4 + Bx2y2 + Cy4), then what is the value of (A2 - B2 + C2)?

Show answer & explanation

Correct answer: A

Explanation

The correct answer is Option 1 i.e. 18.

a3 - b3 = (a - b)(a2 + ab + b2)

8x6 - 6√6y6 = (2x2 + Ay2)(4x4 + Bx2y2 + Cy4)

⇒ (2x2 - √6y2)(4x4 + 2√6x2y2 + 6y4) = (2x2 + Ay2)(4x4 + Bx2y2 + Cy4)

Now, comparing the equation

A = -√6; B = 2√6; C = 6

A2 - B2 + C2 = (-√6)2 - (2√6)2 + 62 = 6 - 24 + 36 = 18