EMNA Q.10
0. When x + y + z = 9 and xy + yz + zx = 11, then x3 - y3 - z3 - 3xyz equals
- Option : C
- Explanation :
x3 - y3 - z3 - 3xyz = (x+y+z)(x2+y2+z2-xy-yz-zx) = 9[(x + y + z)2 - 3(xy + yz + zx)] = 9(81 - 33) = 432.
0. When x + y + z = 9 and xy + yz + zx = 11, then x3 - y3 - z3 - 3xyz equals
x3 - y3 - z3 - 3xyz = (x+y+z)(x2+y2+z2-xy-yz-zx) = 9[(x + y + z)2 - 3(xy + yz + zx)] = 9(81 - 33) = 432.
