We are given the expression x³ - 2y² - 3x³ + z⁴. We have to evaluate it at a given set of x, y, and z values. Before then, let's combine like terms.
x³ - 2y² - 3x³ + z⁴
= -2x³ - 2y² + z⁴ <-- by combining like terms
Now we evaluate for x=3 y=5 z = -3
= -2(3³) - 2(5²) + (-3⁴) <-- by putting in for x, y, z
= -2(27) - 2(25) + 81 <--- parentheses and exponents first in order of operations
= -54 - 50 + 81 <---- multiplication is next
= -4 + 81
= 77
Thus, we evaluate and it's 77.