1nishant bhaiyya i m not able to get this question,bcoz the ans is 6.
\120dpi \; \; LET A ={2,3,4,5,.........17,18}.LET \simeq BE \:\; THE\; \; EQUIVALENCE\; \; RELATION\; \; ON\; \; A\times A,\; \; DEFINED\; \; BY\; (a.b)\simeq (c.d)\; \; iff\; \; ad=bc.\; \; THEN\; \; THE\; \; NO\; \; OF\; \; ORDERED\; \; PAIRS\; \; OF\; \; THE\: \; EQUIVALENCE\: \; CLASS\; \; OF\; \; (3.2)\; \; IS? l
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5 Answers
62This one is not very difficult..
It just means that a/b=c/d
so the fraction should be unique..
Then the number of such pairs will be
2/2, 2/3, 2/4, 2/5, 2/6, 2/7, 2/8, 2/9, 2/10, 2/11, 2/12, 2/13, 2/14, 2/15, 2/16, 2/17, 2/18
I cant think of a very simple method other than counting.. this counting can be made simpler but not beyond a point worth writing here :)
62oh i din see the full question because the image was visible only partly..
Now i can read the last part of the question (3,2)
:P
See here you have to find the number of elements (a,b) satisfying a/b=3/2
whihc is given by
3,2
6,4
9, 6
12, 8
15, 10
18, 12
which is 6