The domain of $f(x)=\sqrt{x-1}$ is:
A$(-\infty,1]$
B$\mathbb{R}$
C$(1,\infty)$
D$[1,\infty)$
Answer & Solution
Correct answer: D. $[1,\infty)$
Need x−1 ≥ 0 ⟹ x ≥ 1, so domain is [1, ∞).
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