Well,
this is from OG 12
If . represents one of the operations +, -, and x, is k. (l+m)=(k.l) + (k.m) for all numbers k, l, and m?
(1) k.1 is not equal to 1.k for some numbers k.
(2) . represents subtraction
it says OA is D as it says substration can be only operation and we can get some value
Agreed
BUT
Lets take,
case 1) k=1,l=2 and m=3
1-(2+3) = (1-2)+(1-3) from question
-4=-3
not true answer NO
now take
k=m=n=0
(question doesnt say we cannot do that neither it says numbers are positive....it says for all numbers....0 is number as well)
0=0
true
Answer is YES
now how is answer D
It is still not giving concrete answer
thanks
Difficulty in understanding this DS Q
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As you calculated take first statement.
k = 0
k-1 != 1-k
where as if l,m = 1,1 respectively then k. (l+m)=(k.l) + (k.m)
k=1
where as if l,m = 2,3 then k. (l+m)!=(k.l) + (k.m) for subtraction and addition
k=1 and l=1,m=-1 then k. (l+m)!=(k.l) + (k.m) for multiplication.
with first statement we can decide whether they are equal or not.
consider second statement
if . represents subtraction then
k = 0
where as if l,m = 1,1 respectively then k. (l+m)=(k.l) + (k.m)
k=1
where as if l,m = 2,3 then k. (l+m)!=(k.l) + (k.m)
which is enough to decide statements are equal or not.
So I think we can decide with any one of the statements.
k = 0
k-1 != 1-k
where as if l,m = 1,1 respectively then k. (l+m)=(k.l) + (k.m)
k=1
where as if l,m = 2,3 then k. (l+m)!=(k.l) + (k.m) for subtraction and addition
k=1 and l=1,m=-1 then k. (l+m)!=(k.l) + (k.m) for multiplication.
with first statement we can decide whether they are equal or not.
consider second statement
if . represents subtraction then
k = 0
where as if l,m = 1,1 respectively then k. (l+m)=(k.l) + (k.m)
k=1
where as if l,m = 2,3 then k. (l+m)!=(k.l) + (k.m)
which is enough to decide statements are equal or not.
So I think we can decide with any one of the statements.
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You're misinterpreting the question, which asks:frank1 wrote:Well,
this is from OG 12
If . represents one of the operations +, -, and x, is k. (l+m)=(k.l) + (k.m) for all numbers k, l, and m?
(1) k.1 is not equal to 1.k for some numbers k.
(2) . represents subtraction
it says OA is D as it says substration can be only operation and we can get some value
Agreed
BUT
Lets take,
case 1) k=1,l=2 and m=3
1-(2+3) = (1-2)+(1-3) from question
-4=-3
not true answer NO
now take
k=m=n=0
(question doesnt say we cannot do that neither it says numbers are positive....it says for all numbers....0 is number as well)
0=0
true
Answer is YES
now how is answer D
It is still not giving concrete answer
thanks
Does k#(l+m) = (k#l) + (k#m) for ALL numbers k, l, and m?
If # represents multiplication:
k*l + k*m = (k*l) + (k*m) will be true for all values of k, l and m.
If # represents addition:
k+l+m = k+l + k+m will be true for some values (if k=0, for example) but not for ALL values of k, l, and m.
If # represents subtraction:
k-l-m = k-l + k-m will be true from some values (if k=0, for example) but not for ALL values of k, l. and m.
Since each statement indicates that # represents subtraction, we know that k-l-m = k-l + k-m will not be true for ALL values of k, l, and m. Thus, each statement is sufficient.
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thanks guru for the response.GMATGuruNY wrote: Since each statement indicates that # represents subtraction, we know that k-l-m = k-l + k-m will not be true for ALL values of k, l, and m. Thus, each statement is sufficient.
i think that is what my question is about
what if k=l=m=0
in that case the above statement will be true 0=0
i think as said earlier,i think question doesnt stop us from taking k=l=m=0
thanks
just a query
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frank1 wrote:thanks guru for the response.GMATGuruNY wrote: Since each statement indicates that # represents subtraction, we know that k-l-m = k-l + k-m will not be true for ALL values of k, l, and m. Thus, each statement is sufficient.
i think that is what my question is about
what if k=l=m=0
in that case the above statement will be true 0=0
i think as said earlier,i think question doesnt stop us from taking k=l=m=0
thanks
just a query
Yes, if # represents subtraction, we could plug in k=l=m=0, in which case k-(l+m) = (k-l) + (k-m). But the answer to the question Does k-(l+m) = (k-l) + (k-m) for ALL numbers k, l, and m? will still be a definitive NO, because k-(l+m) = (k-l) + (k-m) is not true for ALL numbers k, l, and m.
Here's an analogy:
Does John eat ice cream every day?
If John eats ice cream on Tuesdays but not on Wednesdays, the answer to the question is NO: John does not eat ice cream every day.
The same reasoning holds true for the DS question above:
Does k#(l+m) = (k#l) + (k#m) for all numbers k, l, and m?
If k#(l+m) = (k#l) + (k#m) when k=l=m=0 but not when k=1, l=2, and m=3, then the answer to the question is NO: k#(l+m) = (k#l) + (k#m) is not true for all numbers k, l, and m.
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Hi GMATGuruNY:
So it could be simply stated then when a question of this type asked in DS
Eg:Does k#(l+m) = (k#l) + (k#m) for all numbers k, l, and m?
No need to look into any of the conditions given as whatever the conditions would be we can Yes/No and the answer would be D always.
So it could be simply stated then when a question of this type asked in DS
Eg:Does k#(l+m) = (k#l) + (k#m) for all numbers k, l, and m?
No need to look into any of the conditions given as whatever the conditions would be we can Yes/No and the answer would be D always.
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Hi Uva,Uva@90 wrote:Hi All,
Can anyone please share any similar kind of questions.
Thanks in advance.
Regards,
Uva.
Here are two similar questions:
- https://www.beatthegmat.com/operation-t45094.html
- https://www.gmatprepnow.com/module/gmat- ... ic?id=1058
Cheers,
Brent
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Thanks Brent:)Brent@GMATPrepNow wrote:Hi Uva,Uva@90 wrote:Hi All,
Can anyone please share any similar kind of questions.
Thanks in advance.
Regards,
Uva.
Here are two similar questions:
- https://www.beatthegmat.com/operation-t45094.html
- https://www.gmatprepnow.com/module/gmat- ... ic?id=1058
Cheers,
Brent
You are always Helpful.
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That's a good point. Even, I was thinking the same, assuming the question format remains the same and we can anyway answer the statements with a definitive 'Yes' or 'No'.uniquer wrote:Hi GMATGuruNY:
So it could be simply stated then when a question of this type asked in DS
Eg:Does k#(l+m) = (k#l) + (k#m) for all numbers k, l, and m?
No need to look into any of the conditions given as whatever the conditions would be we can Yes/No and the answer would be D always.
Experts - Please correct if we are missing anything in our understanding. Is this a very broad assumption to make for such type of questions ?
Best Regards,
Rahul Sehgal
Rahul Sehgal