SOLUTION: The sum of the squares of the digits of a certain two digit positive integer is 20. The integer is seven times the sum of its digits. Find the integer.

Question 955037: The sum of the squares of the digits of a certain two digit positive integer is 20. The integer is seven times the sum of its digits. Find the integer.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The sum of the squares of the digits of a certain two digit positive integer is 20. The integer is seven times the sum of its digits. Find the integer.
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Let the number be 10t+u
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Equation:
t^2 + u^2 = 20
10t+u = 7(t+u)
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Simplify::
t^2 + u^2 = 20
t = 2u
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Substitute and solve for "u":
4u^2 + u^2 = 20
5u^2 = 20
u = 2 or u = -2
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If u = 2, t = 4 giving you 10t+u = 42
if u = -2, t = -4 giving you 10t+u = -42
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Cheers,
Stan H.
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