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Age function (Posted on 2023-08-17) Difficulty: 2 of 5
A polynomial f with integer coefficients is written on the blackboard. The teacher is a mathematician who has 3 kids named Andrew, Beth and Charles. Andrew, who is 7, is the youngest, and Charles is the oldest. When evaluating the polynomial on his kids' ages he obtains:

f(7) = 77
f(b) = 85, where b is Beth's age,
f(c) = 0, where c is Charles' age.

How old is each child?

No Solution Yet Submitted by Danish Ahmed Khan    
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soln | Comment 1 of 7
Ages: 7, 9, 14

f(x) = -3 x^2 + 52 x -140

f(7) = 77
f(9) = 85
f(14) = 0

I just poked around a bit using a computer search. 
I started with up to 8th order polynomials, but then
I noticed the problem's difficulty was rated low, so I dropped down to 
quartics and larger coefficients, and the answer just popped out. 

Edited on August 18, 2023, 1:38 am
  Posted by Steven Lord on 2023-08-18 01:36:56

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