Question

if x+y+z=5,xy+yz+zx=-1 and xyz=-1 find the value of x³+y³+z³​

Answer 1

x³+y³+z³-3xyz=(x+y+z)(x²+y²+z²-xy-yz-zx)

x³+y³+z³=(x+y+z)(x²+y²+z²-xy-yz-zx)+3xyz

x³+y³+z³=1x(x+y+z)²-1+3x-1

=1-1-3

=-3