They are just asking us to plug in (-4) wherever you see an x, a 3 wherever you see y and 2 wherever you see z.
[tex] 2*(-4)^2-2(2)^4+3^2-(-4)^2+2^4\\32-32+9-16+16=9 [/tex]
2x^2 - 2z^4 + y ^2 - x^2 + z^4
Just plug in x = -4, y = 3, and z = 2 into the expression
2(-4)^2 - 2(2)^4 + (3)^2 - (-4)^2 + (2)^4
= 2 * 16 - 2 * 16 + 9 - 16 + 16
= 32 - 32 + 9 - 16 + 16
= 9
