Final answer:
To determine whether a function is a bijection from R to R, we need to check if it is both injective (one-to-one) and surjective (onto). For f(x) = -3x^4, the function is not injective. For f(x) = -3x^2/7, the function is not surjective.
Step-by-step explanation:
To determine whether a function is a bijection from R to R, we need to check if it is both injective (one-to-one) and surjective (onto).
a) For f(x) = -3x^4, we can see that this function is not injective because different values of x can map to the same output (-3x^4 = -3(-x)^4).
b) For f(x) = -3x^2/7, this function is also not a bijection as it is not surjective. The range of this function is (0, infinity), which means there are values in the codomain that are not covered by the function.