If x + y + z = 6 and x2 + y2 + z2 = 20, then the value of x3 + y3 + z3 - 3xyz is
64
70
72
76
If (x + y) = 1, then the value of
is
3
-3
1
-1
A.
3
x.y (x + y) = 1
On cubing both sides,
[x. y (x + y)3] = (1)3
x3. y3 [x3 + y3 + 3xy (x + y)] = 1
Given, x. y(x + y) = 1