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Find the domain and range of the following real function: (i) f(x) = –|x| (ii) () = √(9 − 2) |
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Answer» (i) f(x) = –|x|, x ∈ R We know that || = { , ≥ 0; −, < 0 ∴ () = −|| = { −, ≥ 0 ; , < 0 Since f(x) is defined for x ∈ R, the domain of f is R. It can be observed that the range of f(x) = –|x| is all real numbers except positive real numbers. ∴ The range of f is (−∞, 0]. (ii) () = √(9 − 2) Since √(9 − 2) is defined for all real numbers that are greater than or equal to –3 and less than or equal to 3, the domain of f(x) is {x : –3 ≤ x ≤ 3} or [–3, 3]. For any value of x such that –3 ≤ x ≤ 3, the value of f(x) will lie between 0 and 3. ∴The range of f(x) is {x: 0 ≤ x ≤ 3} or [0, 3]. |
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