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mingshum
Senior Member

USA
29 Posts

Posted - 01/10/2009 :  17:44:09  Show Profile  Reply with Quote
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??
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Mrspi
Advanced Member

USA
998 Posts

Posted - 01/10/2009 :  18:19:08  Show Profile  Reply with Quote
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?
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mingshum
Senior Member

USA
29 Posts

Posted - 01/10/2009 :  19:28:36  Show Profile  Reply with Quote
Thank you Mrspi!!! How could I have forgotten to simplify the radical!
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