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December 30, 2005
quadraticsalgebraquadratic formula

Problem Statement

How many pairs (a,b)(a,b) of non-zero real numbers satisfy the equation 1a+1b=1a+b? \frac{1}{a} + \frac{1}{b} = \frac{1}{a+b}? (A) none(B) 1(C) 2(D) one pair for each b0\text{(A)} \ \text{none} \qquad \text{(B)} \ 1 \qquad \text{(C)} \ 2 \qquad \text{(D)} \ \text{one pair for each} ~b \neq 0 (E) two pairs for each b0\text{(E)} \ \text{two pairs for each} ~b \neq 0