If f(x)=x+7−2f(x) = \sqrt{x+7} - 2f(x)=x+7−2, what is the domain of its inverse function f−1(x)f^{-1}(x)f−1(x)?
x≥−2x \ge -2x≥−2
x≥0x \ge 0x≥0
x≥−7x \ge -7x≥−7
All real numbers