Question

If x+y+ z = 8 and xy +yz+zx = 20 find the value of x3

+y3

+z3

-3xyz.​

Answer 1

Answer:

x^3+y^3+z^3-3xyz

=(x+y+z)(x^2+y^2+z^2-xy-yz-zx)

=8{(x+y+z)^2-2(xy+yz+zx)-(xy+yz+zx)}

=8{(8)^2-3(xy+yz+zx)}

=8{64-3.20}

=8{64-60)

=8.4

=32