saeed wrote: Q3. Is x>k?
1. (2x)(2k)=4
2. (9x)(3k)=81.

Please help me with most efficient approach.
Thanks in advance.

Ian Stewart wrote:

jeffxujian wrote:

Ian Stewart wrote:I'm pretty sure Q3 is supposed to read:

Q3. Is x>k?
1. (2^x)(2^k)=4
2. (9^x)(3^k)=81.

Then the statements are not contradictory.

Ian:

Is the correct answer of the above question C?

1. x+k=4 insufficient, because x, k can be any numbers
2.2x+k=4 insufficient, same drill as above

combine 1 with 2, x=0 and K=4, thus the result is sufficient to answer question whether x is greater than k.

Please correct me if i made any mistakes. Thank!

Yes, it is C, though your first equation should read x+k = 2. If you solve, you should find x=2 and k=0.