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QJEEM24Ma049f: JEE Main 2024 Mathematics - Class 11 JEEM24Ma049f Solution: Let the relations and on the set be given by and . If and be…

Let the relations R1R_1 and R2R_2 on the set X={1,2,3,…,20}X=\{1,2,3, \ldots, 20\} be given by R1={(x,y):2x−3y=2}R_1=\{(x, y): 2 x-3 y=2\} and R2={(x,y):−5x+4y=0}R_2=\{(x, y):-5 x+4 y=0\} . If MM and NN be the minimum number of elements required to be added in R1R_1 and R2R_2 , respectively, in order to make the relations symmetric, then M+NM+N equals

Multiple Choice Options

  • A 16
  • B 12
  • C 8
  • D 10

Step-by-Step Verified Solution

amp;R1={(x,y):2x−3y=2}amp;R2={(x,y):−5x+4y=0}amp;2x−3y=2\begin{aligned}& R_1=\{(x, y): 2 x-3 y=2\} \\& R_2=\{(x, y):-5 x+4 y=0\} \\& 2 x-3 y=2\end{aligned}

So 2x2 x and 3y3 y both has to be even or odd simultaneously and 2x2 x can't be odd so 2x2 x and 3y3 y both will be even

R1={(4,2),(7,4),(10,6),(13,8),(16,10),(19,12)}R_1=\{(4,2),(7,4),(10,6),(13,8),(16,10),(19,12)\}

For symmetric we need to add 6 elements as

amp;(2,4),(4,7),(6,10),(8,13),(10,16),(12,19)amp;M=6\begin{aligned}& (2,4),(4,7),(6,10),(8,13),(10,16),(12,19) \\& M=6\end{aligned}

For R2−5x+4y=0R_2-5 x+4 y=0

5x5 x and 4y4 y has to be equal 4y4 y is always even so 5x5 x will also be even

R2={(4,5),(8,10),(12,15),(16,20)}R_2=\{(4,5),(8,10),(12,15),(16,20)\}

For symmetric we need to add 4 element as

amp;(5,4)(10,8)(15,12)(20,16)amp;N=4amp;M+N=6+4=10\begin{aligned}& (5,4)(10,8)(15,12)(20,16) \\& N=4 \\& M+N=6+4=10\end{aligned}

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