方程兩邊同除以 xy,得 1 + 1/y + 1 + 1/x = 12x/y + 12/y
( 12x + 11)/y = ( 2x + 1 )/x
y/x = ( 12x + 11)/( 2x + 1 ) = ( 12x + 6 )/( 2x + 1 ) + 5/( 2x + 1 ) = 6 + 5/( 2x + 1 );
若 y/x 是正整數(shù),則5/( 2x + 1 ) 是正整數(shù),x = 2;
y/2 = 6 + 1,y = 14;
將 x = 2,y = 14 代入方程,成立。
∴ x + y = 2 + 14 = 16