1380.11 – Some Sums


Nilcha is thinking of two numbers. The sum of the numbers is three, he says, and the sum of their squares is twenty-nine. What two numbers is Nilcha thinking of?


Solution

Nilcha’s numbers are five and negative two, found by solving simultaneous equations: x+y=3x + y = 3 and x2+y2=29x^2 + y^2 = 29 With such small numbers, guess work suffices, remembering that one of the numbers can, in fact must be, negative.