Determine the range of f(x)=∣x−3∣+∣x+3∣f(x) = |x-3| + |x+3|f(x)=∣x−3∣+∣x+3∣.
[0,∞)[0, \infty)[0,∞)
[6,∞)[6, \infty)[6,∞)
(0,∞)(0, \infty)(0,∞)
All real numbers