Find the domain and range of the following functions:
a. f: ℝ → ℝ by f(x) = −x2 + 2
b. f: ℝ → ℝ by f(x) = 1 / x + 1
c. f: ℝ → ℝ by f(x) = √4 − x
d. f: ℝ → ℝ by f(x) = |x|
e. f: ℝ → ℝ by f(x) = 2x+2