Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

Which of the following statement is correct?

I. If x = 12, y = -2 and z = -10, then $x^3+y^3+z^3=720$

II. If x + y = 48 and 4xy = 128, then s the value of $4x^2 +4y^2 is 8960$

Options:

Neither I nor II

Only I

Both I and II

Only II

Correct Answer:

Both I and II

Explanation:

I. If x = 12, y = -2 and z = -10, then $x^3+y^3+z^3=720$

$x^3+y^3+z^3$ = 123 + (-2)3 + (-10)3

$x^3+y^3+z^3$  = 1728 - 8 - 1000 = 720

II. If x + y = 48 and 4xy = 128, then s the value of $4x^2 +4y^2 is 8960$

$x^3+y^3$ = 4 ( x2 + y2 )  = 4 (x2 + y2 + 2xy)

xy  = \(\frac{128}{4}\) = 32

482 = (  x2 + y2 + 2 × 32 ) 

x2 + y2 = 2240

4 ( x2 + y2 ) = 4 × 2240 = 8960

Both I and II