Author 
Topic 

mingshum
Senior Member
USA
29 Posts 
Posted  01/10/2009 : 17:44:09

If 1818 = rt where r and t are positive integers and r > t, which of the following could be the value of rt?
A)18 B)36 C)108 D)162 E)324
I squared both sides of the equation and came up with 3 to the sixth power times 2= rt
So I concluded that r = 3and t = 2 thus rt = 216 which is not a choice! The answer is 108. Where did my reasoning go wrong?? 


Mrspi
Advanced Member
USA
998 Posts 
Posted  01/10/2009 : 18:19:08

quote: Originally posted by mingshum
If 1818 = rt where r and t are positive integers and r > t, which of the following could be the value of rt?
A)18 B)36 C)108 D)162 E)324
I squared both sides of the equation and came up with 3 to the sixth power times 2= rt
So I concluded that r = 3and t = 2 thus rt = 216 which is not a choice! The answer is 108. Where did my reasoning go wrong??
Did you think about simplifying
18 18 18 18 = 18 9 * 2 18 18 = 18*32
Or,
1818 = 542
Now... if this = r t, then
r = 54 and t = 2
Looks to me like r = 54, and t = 2
So, what could be the value of r*t? 


mingshum
Senior Member
USA
29 Posts 
Posted  01/10/2009 : 19:28:36

Thank you Mrspi!!! How could I have forgotten to simplify the radical! 



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