Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $(16\sqrt{2}x^3 + 81\sqrt{3}y^3) \div (2\sqrt{2}x + 3\sqrt{3}y) = Ax^2 + By^2 + Cxy$, then find the value of $2A - 3B - 2\sqrt{6} C$.

Options:

25

7

137

79

Correct Answer:

7

Explanation:

a3 + b3 = (a + b)(a2 + b2 - ab)

= (16√2x3 + 81√3y3) ÷ (2√2x + 3√3y) = Ax2 + By2 + Cxy

= Ax2 + By2 + Cxy = [(2√2x + 3√3y)(8x2 + 27y2 - 2√2x × 3√3y)]/(2√2x + 3√3y)

= Ax2 + By2  + Cxy = (8x2 + 27y2 - 2√2x × 3√3y)

= Ax2 + By2  + Cxy = (8x2 + 27y2 - 6√6xy)

A = 8, B = 27 and C = -6√6

The value of $2A - 3B - 2\sqrt{6} C$ = $2 × 8  - 3 × 27  - 2\sqrt{6}  × -6√6 $ = 7