Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x + y + z = 2, xy + yz + zx = -11, and xyz = -12, then what is the value of x3 +y3 +z3 ?

Options:

36

38

40

42

Correct Answer:

38

Explanation:

x3 + y3 + z3 – 3xyz = (x + y +z) [(x + y + z)2 – 3(xy + yz + zx)]

= x3 + y3 + z3 – 3 × (–12) = 2[22 – 3 × (– 11)]

= x3 + y3 + z3 + 36 = 2[4 + 33]

= x3 + y3 + z3 + 36 = 2 × 37

= x3 + y3 + z3 = 74 – 36 = 38