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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)18B)36C)108D)162E)324I squared both sides of the equation and came up with 3 to the sixth power times 2= rtSo 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

USA
998 Posts

 Posted - 01/10/2009 :  18:19:08 quote:Originally posted by mingshumIf 1818 = rt where r and t are positive integers and r > t, which of the following could be the value of rt?A)18B)36C)108D)162E)324I squared both sides of the equation and came up with 3 to the sixth power times 2= rtSo 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 1818 18 = 18 9 * 218 18 = 18*32Or, 1818 = 542Now... if this = r t, thenr = 54and t = 2Looks to me like r = 54, and t = 2So, 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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