Find the number of integral ordered pairs such that:
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The given equation can be rewritten as x y x + y = 1 0 0 1 ⟹ x y = 1 0 0 ( x + y ) ⟹ x y − 1 0 0 x − 1 0 0 y = 0 ⟹ ( x − 1 0 0 ) ( y − 1 0 0 ) = 1 0 0 0 0 .
Now since 1 0 0 0 0 = 2 4 5 4 this value has ( 4 + 1 ) ( 4 + 1 ) = 2 5 positive integer divisors, and thus 2 × 2 5 = 5 0 integer divisors in general, (i.e., a negative divisor mirroring each positive divisor). So we can represent 1 0 0 0 0 as a pairwise product a b in 5 0 distinct ways, assigning a = x − 1 0 0 , b = y − 1 0 0 , which in turn gives us 5 0 distinct pairs ( x , y ) . However, one of these pairs is ( a , b ) = ( − 1 0 0 , − 1 0 0 ) ⟹ ( x , y ) = ( 0 , 0 ) , which would not satisfy the original equation. Thus we are left with a final total of 4 9 ordered integer pair solutions to the given equation.