The elements ,X ,Y and Z react as follows
` X_(2)O_(3) + 2Y to Y_(2)O_(3) +2X`
` Y_(2) O_(3) +3C to 3CO +2Y`
Arrange the elements X,Y and Z in the order of their decreasing reactivity.

X, Y, Z are three elements, which undergo chemical changes according to the following equation: I: X_(2)O_(3)+2Y to Y_(2)O_(3)+2X II:Y_(2)O_(3)+3Z to 3ZO+2Y The order of increasing reactivity is

The value of the expression ((x ^(2) - y ^(2)) ^(3) + ( y ^(2) - z ^(2)) ^(3) + (z ^(2) - x ^(2)) ^(3))/((x - y) ^(3) + ( y - z) ^(3) + (z - x ) ^(3)) is

3x - [4y - {7x - (3z - 2y) + 4z - 3(x + 3y - 2z)}]