Let A={−2,−1,0,1,2,3}A=\{-2,-1{,}0{,}1{,}2{,}3\}. Define a relation RR on AA by xRyxRy if and only if y=max⁡(x,1)y=\max(x,1). If ll is the number of elements in RR, and mm and nn are the minimum numbers of ordered pairs that must be added to RR to make it reflexive and symmetric respectively, then l+m+nl+m+n is equal to:

Answer: 12

Step-by-step solution

Step 1: Determine the relation R and its size l

The relation RR is defined for elements x,yx, y in set AA such that yy is the maximum of xx and 11. We need to find all ordered pairs (x,y)(x,y) that satisfy this condition for each x∈Ax \in A. We will then count the number of elements in RR, which is ll.

Step 2: Calculate the elements of R

For each x∈Ax \in A: - If x=−2x = -2, max⁡(−2,1)=1\max(-2{,}1) = 1, so (−2,1)∈R(-2{,}1) \in R. - If x=−1x = -1, max⁡(−1,1)=1\max(-1{,}1) = 1, so (−1,1)∈R(-1{,}1) \in R. - If x=0x = 0, max⁡(0,1)=1\max(0{,}1) = 1, so (0,1)∈R(0{,}1) \in R. - If x=1x = 1, max⁡(1,1)=1\max(1{,}1) = 1, so (1,1)∈R(1{,}1) \in R. - If x=2x = 2, max⁡(2,1)=2\max(2{,}1) = 2, so (2,2)∈R(2{,}2) \in R. - If x=3x = 3, max⁡(3,1)=3\max(3{,}1) = 3, so (3,3)∈R(3{,}3) \in R. Thus, R={(−2,1),(−1,1),(0,1),(1,1),(2,2),(3,3)}R = \{(-2{,}1), (-1{,}1), (0{,}1), (1{,}1), (2{,}2), (3{,}3)\}. The number of elements in RR is l=6l = 6.

Step 3: Determine m for reflexivity

For a relation to be reflexive, every element x∈Ax \in A must have (x,x)∈R(x,x) \in R. The set A={−2,−1,0,1,2,3}A = \{-2,-1{,}0{,}1{,}2{,}3\}. The reflexive pairs are (−2,−2),(−1,−1),(0,0),(1,1),(2,2),(3,3)(-2,-2), (-1,-1), (0{,}0), (1{,}1), (2{,}2), (3{,}3). From RR, we have (1,1),(2,2),(3,3)(1{,}1), (2{,}2), (3{,}3). The missing reflexive pairs are (−2,−2),(−1,−1),(0,0)(-2,-2), (-1,-1), (0{,}0). Therefore, m=3m = 3 pairs must be added to make RR reflexive.

Step 4: Determine n for symmetry

For a relation to be symmetric, if (x,y)∈R(x,y) \in R, then (y,x)(y,x) must also be in RR. We check each pair in RR: - (−2,1)∈R(-2{,}1) \in R, but (1,−2)∉R(1,-2) \notin R. So, (1,−2)(1,-2) must be added. - (−1,1)∈R(-1{,}1) \in R, but (1,−1)∉R(1,-1) \notin R. So, (1,−1)(1,-1) must be added. - (0,1)∈R(0{,}1) \in R, but (1,0)∉R(1{,}0) \notin R. So, (1,0)(1{,}0) must be added. - (1,1)∈R(1{,}1) \in R, and (1,1)∈R(1{,}1) \in R. No addition needed. - (2,2)∈R(2{,}2) \in R, and (2,2)∈R(2{,}2) \in R. No addition needed. - (3,3)∈R(3{,}3) \in R, and (3,3)∈R(3{,}3) \in R. No addition needed. Therefore, n=3n = 3 pairs must be added to make RR symmetric.

Step 5: Calculate l + m + n

We have found l=6l=6, m=3m=3, and n=3n=3. Now we sum these values to get the final answer.

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