2a-3b+c=0,①
a-2b-2c=0,②
①-②×2,得,
b=-5c,
代人①,得,
a=-8c,
将a=-8c,b=-5c代人到代数式中,得,
a^2-2b^2-8c^分之ab+4bc+2ab
=(ab+4bc+2ab)/(a^2-2b^2-8c^2)
=(40c^2-20c^2+80c^2)/(64c^2-50c^2-8c^2)
=100c^2/6c^2
=50/3