Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x4 + x2y2 + y4 = 273

x2 - xy + y2 = 13, then

find xy.

Options:

2

6

4

8

Correct Answer:

4

Explanation:

Formula → x4 + y4 + x2y2 = (x+ y2 + xy) × (x+ y2 - xy)

⇒ 273 = 13 × (x+ y2 + xy)

⇒ x+ y2 + xy = \(\frac{273}{13}\)

⇒ x+ y2 + xy = 21                 ............(i)

⇒ x+ y2 -  xy = 13    (given) .............(ii)

(i) - (ii),

⇒ 2xy = 8

⇒ xy = 4