The following functions all have {1,2, 3,4, 5} as both their
domain and codomain. For each, determine whether it is
(only) injective, (only) surjective, bijective, or neither
injective nor surjective.
Neith 15 1 2 3 45
I r < . =
eine 2 4312
sujectveo Jair
urjective . = 4 4 2 3 1
1 2 3 45
Bijecti ¢ [[8Sfi=
ijective if: (; 43 1 :)
Gr oo _J4-z ifz
Question:
The following functions all have {1,2, 3,4, 5} as both their
domain and codomain. For each, determine whether it is
(only) injective, (only) surjective, bijective, or neither
injective nor surjective.
Neith 15 1 2 3 45
I r < . =
eine 2 4312
sujectveo Jair
urjective . = 4 4 2 3 1
1 2 3 45
Bijecti ¢ [[8Sfi=
ijective if: (; 43 1 :)
Gr oo _J4-z ifz
This is AI generated Response.
Asked by: Test User 100047
Created at: 2025-05-13 05:49:58
Final Answer:
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Let's analyze each function:
### 1. \( f = \begin{pmatrix} 1 & 2 & 3 & 4 & 5 \\ 2 & 4 & 3 & 1 & 2 \end{pmatrix} \)
- **Domain:** {1, 2, 3, 4, 5}
- **Codomain:** {1, 2, 3, 4, 5}
- **Mapping:** 1→2, 2→4, 3→3, 4→1, 5→2
- **Injective?** No, since 1 and 5 both map to 2.
- **Surjective?** No, 5 is not in the range.
- **Answer:** **Neither**
### 2. \( f = \begin{pmatrix} 1 & 2 & 3 & 4 & 5 \\ 4 & 4 & 2 & 3 & 1 \end{pmatrix} \)
- **Mapping:** 1→4, 2→4, 3→2, 4→3, 5→1
- **Injective?** No, since 1 and 2 both map to 4.
- **Surjective?** Yes, range is {1, 2, 3, 4}.
- **But codomain is {1, 2, 3, 4, 5}.** So 5 is missing, not surjective.
- **Correction:** **Neither**
### 3. \( f = \begin{pmatrix} 1 & 2 & 3 & 4 & 5 \\ 2 & 4 & 3 & 1 & 5 \end{pmatrix} \)
- **Mapping:** 1→2, 2→4, 3→3, 4→1, 5→5
- **Injective?** Yes, all outputs are unique.
- **Surjective?** Yes, covers all elements in codomain.
- **Answer:** **Bijective**
### 4. \( f(x) = \begin{cases} 4-x & \text{if } x<4 \\ 9-x & \text{if } x \geq 4 \end{cases} \)
- Let's check for x = 1, 2, 3, 4, 5:
- x = 1: 4-1 = 3
- x = 2: 4-2 = 2
- x = 3: 4-3 = 1
- x = 4: 9-4 = 5
- x = 5: 9-5 = 4
- Outputs: {1, 2, 3, 4, 5}
- **Injective?** Yes, all outputs are unique.
- **Surjective?** Yes, all elements of codomain are hit.
- **Answer:** **Bijective**
**Summary of correct answers:**
1. Neither
2. Neither (not Surjective)
3. Bijective
4. Bijective
**Note:** You have marked 2 as "Surjective", but it should be "Neither".
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