Match List-I with List-II
Where R is set of real numbers
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List-I |
List-II |
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(A) $f: R→R$ s.t $f(x) = x^4$ is |
(I) one-one, Into |
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(B) $f: R→[0, ∞)$ s.t $f(x) = x^4$ is |
(II) many-one, into |
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(C) $f: [0, ∞)→R$ s.t $f(x) = x^4$ is |
(III) one-one, onto |
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(D) $f: [0, ∞)→[0, ∞)$ s.t $f(x) = x^4$ is |
(IV) many-one, onto |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A)-(II), (B)-(IV), (C)-(I), (D)-(III)
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List-I |
List-II |
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(A) $f: R→R$ s.t $f(x) = x^4$ is |
(II) many-one, into |
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(B) $f: R→[0, ∞)$ s.t $f(x) = x^4$ is |
(IV) many-one, onto |
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(C) $f: [0, ∞)→R$ s.t $f(x) = x^4$ is |
(I) one-one, Into |
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(D) $f: [0, ∞)→[0, ∞)$ s.t $f(x) = x^4$ is |
(III) one-one, onto |
Explanation:
(A) $f:\mathbb{R} \to \mathbb{R}$, $f(x)=x^{4}$
For $x$ and $-x$, $f(x)$ is the same, so it is many-one. The range is $[0,\infty)$, which is a subset of $\mathbb{R}$, so not onto. Matches (II).
(B) $f:\mathbb{R} \to [0,\infty)$, $f(x)=x^{4}$
Still many-one because $x$ and $-x$ map to the same value, but now the range exactly matches the codomain $[0,\infty)$, so it is onto. Matches (IV).
(C) $f:[0,\infty) \to \mathbb{R}$, $f(x)=x^{4}$
For $x\ge0$, $f$ is strictly increasing, so one-one. The range is $[0,\infty)$, which is a subset of $\mathbb{R}$, so not onto. Matches (I).
(D) $f:[0,\infty) \to [0,\infty)$, $f(x)=x^{4}$
For $x\ge0$, $f$ is strictly increasing, so one-one. The range is $[0,\infty)$, which matches the codomain, so onto. Matches (III).