Which of the following functions has an inverse that is also a function?
f(x)=x2f(x) = x^2f(x)=x2
f(x)=5f(x) = 5f(x)=5
f(x)=2x−3f(x) = 2x - 3f(x)=2x−3
f(x)=∣x∣f(x) = |x|f(x)=∣x∣