(1) If X = 1, Y = 1, Z = 2, then X² - Y^3 - 2Z = 1 - 1 - 4 = -4, which is even.arjunshn wrote:If X, Y and Z are non-zero numbers, is X2- Y3- 2Z odd?
(1) X and Y are odd
(2) Z is even
If X = 1, Y = 1, Z = 3/2, then X² - Y^3 - 2Z = 1 - 1 - 3 = -3, which is odd.
No unique answer, which implies X² - Y^3 - 2Z may or may not be odd.
So, (1) is NOT SUFFICIENT.
(2) If X = 1, Y = 2, Z = 2, then X² - Y^3 - 2Z = 1 - 8 - 4 = -11, which is odd.
If X = 1, Y = 1, Z = 2, then X² - Y^3 - 2Z = 1 - 1 - 4 = -4, which is even.
No unique answer, which implies X² - Y^3 - 2Z may or may not be odd.
So, (2) is NOT SUFFICIENT.
Combining (1) and (2), X, Y are odd and Z is even.
So, X² - Y^3 - 2Z = (ODD)² - (ODD)^3 - 2(EVEN) = ODD - ODD - EVEN = EVEN
Hence, X² - Y^3 - 2Z is even.
The correct answer is C.
