SSC CGL 2020 PYQ — Question 52

The correct answer is option 1 i.e 4

Explanation:

x² - xy + y² = 13 ---(1)

⇒ x⁴ + x² y² + y⁴ = 273

⇒ x² + xy + y²)(x² - xy + y²) = 273 ---(2)

put the value of eq (1) in eq (2)-

(x² + xy + y²)(13) = 273

⇒ (x² + xy + y²) = 21

⇒ (x² + xy + y² + xy - xy) = 21

(x² - xy + y² + 2xy) = 21

put the value from eq(1)

13 + 2xy = 21

⇒ 2xy = 8

⇒ xy = 4

∴ The value of xy is 4.