1/a+1/b=1 (1)
1/b+1/c=2 (2)
1/c+1/a=5 (3)
(1)+(2)+(3)得 2*(1/a+1/b+1/c)=8
1/a+1/b+1/c=4 (4)
(4)-(1) 1/c=3 c=1/3
(4)-(2) 1/a=2 a=1/2
(4)-(3) 1/b=-1 b=-1
再代回去,得到答案
1/a+1/b=1 (1)
1/b+1/c=2 (2)
1/c+1/a=5 (3)
(1)+(2)+(3)得 2*(1/a+1/b+1/c)=8
1/a+1/b+1/c=4 (4)
(4)-(1) 1/c=3 c=1/3
(4)-(2) 1/a=2 a=1/2
(4)-(3) 1/b=-1 b=-1
再代回去,得到答案