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Question 137884: the following is from a worksheet... please help me help my son figure this one out.
The tens digit of a two-digit number is 1 less than five times the units digit. The square of the units digit is 5 less than the tens digit. Find the number.
have tried unsuccessfully to manipulate the following to find the answer:
t=5u-1 and u**2=t-5
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The tens digit of a two-digit number is 1 less than five times the units digit. The square of the units digit is 5 less than the tens digit. Find the number.
have tried unsuccessfully to manipulate the following to find the answer:
t=5u-1 and u**2=t-5
Substitute 1st into 2nd to get:
u^2=5u-1-5
u^2-5u+6 = 0
(u-3)(u-2) = 0
u=3 or u=2
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If u = 3 , t=5*3-1 = 14
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If u=2, t = 5*2-1 = 9
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The ten's digit cannot be 14 so the only solution is 92
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Cheers,
Stan H.
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