2a-3b+c=0,4a-6b+2c=0 3a-2b-6c=0,9a-6b-18c=0 5a=20c,a=4c b=3c a3-2b3+4c3/a2b-2b2c+3ac2 =(64c^3-2*27c^3+4c^3)/(16c^2*3c-2*9c^2*c+3*4c*c^2) =(14c^3)/(42c^3) =1/3