Determine if the functions are even, odd or neither. f (x) = - 5x4 - 2 and g (x) = x3 + 2x

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the rule: if f (-x) = f (x), then the function f (x) is even, if f (-x) = - f (x) then the function is odd.

1. f (x) = - 5x⁴-2;

if to substitute x→ (-x), then f (-x) = - 5 * (-x) ⁴-2; ⇔ f (-x) = - 5x⁴-2, in other words f (x) = f (-x), it means that this function is even.

2. f (x) = x³+2x.

if to substitute x→ (-x), then f (-x) = (-x) ³+2 * (-x); ⇔ f (-x) = - (x³+2x), in other words f (-x) = - f (x), it means that this function is odd.