Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $x^4 + x^2y^2 + y^4 = 133$ and $x^2 - xy + y^2 = 7$, then what is the value of xy?

Options:

8

12

4

6

Correct Answer:

6

Explanation:

If $x^4 + x^2y^2 + y^4 = 133$

$x^2 - xy + y^2 = 7$--- (1)

what is the value of xy?

x4 + x2y2 + y4 = (x– xy + y2) (x2 + xy + y2)

Then , $x^2 + xy + y^2 = \frac{133}{7}$ = 19----- (2)

From equation 1 and 2 we get,

xy = 6