If $x+y+z=1, x y+y z+z x=x y z=-4$, then what is the value of $\left(x^3+y^3+z^3\right)$ ?
Answer & explanation
Correct answer: option 3
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