Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $x+y+z=1, x y+y z+z x=x y z=-4$, then what is the value of $\left(x^3+y^3+z^3\right)$ ?

Options:

8

-8

1

-1

Correct Answer:

1

Explanation:

Given,

x + y + z = 1,

xy + yz + zx = xyz = -4

We know that,

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

According to the question

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

x3 + y3 + z3  – 3(-4) = (1) [(1)2 – 3(-4)]

x3 + y3 + z3 + 12 = (1 + 12)

x3 + y3 + z3  + 12 = 13

x3 + y3 + z3 = (13 – 12)

 (x3 + y3 + z3 ) = 1