Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $2\sqrt{2}x^3 - 3\sqrt{3}y^3 = (\sqrt{2}x- \sqrt{3}y) (Ax^2 - Bxy +Cy^2)$, then the value of $(A^2 +B^2 +C^2)$ is :

Options:

16

11

19

18

Correct Answer:

19

Explanation:

If $2\sqrt{2}x^3 - 3\sqrt{3}y^3 = (\sqrt{2}x- \sqrt{3}y) (Ax^2 - Bxy +Cy^2)$

 $(A^2 +B^2 +C^2)$

We know that =

a3 - b3 = ( a - b ) ( a2 + b2 + ab )

On comparing them we get = 

A = (\(\sqrt {2}\))2 = 2

C = (\(\sqrt {3}\))2 = 3

B = - (\(\sqrt {2}\)) × (\(\sqrt {3}\)) = -\(\sqrt {6}\)

$(A^2 +B^2 +C^2)$ = 22 +(-\(\sqrt {6}\))2 + 32

$(A^2 +B^2 +C^2)$  = 4 + 6 + + 9 = 19