Answer to February 1, 1999 Problem

Reciprocal Riddle
from Problem Solving A Handbook for Teachers
by Krulik and Rudnik

The sum of two numbers is 2,
and the product of these same two numbers is 3.
Determine the sum of their reciprocals.



Solution:

The answer is 2 / 3

Let x and y represent the two numbers. Then
x + y = 2
xy = 3

This yields x = 1 + 1.414 i
and y = 1 - 1.414 i

But there is a more artistic solution:
1/x + 1/y = (x + y) / (xy) = 2 / 3


Correctly solved by:

1. Michael Leatherman Norfolk, VA