a2+6b=-17 (1)
b2+2a=14 (2)
c2+2a=14 (3)
(2)-(3)得 b2-c2=0
b2=c2(4)
(2)+(3)联合(4)得 2b2+4a-28=0 (5)
联解 (1)、(5)得 a、