（2x2+ax-y+6)-(2bx2-3x+5y-1) = 2(1-b)x^2 + (a+3)x +...值与字母x所取的值无关1-b=0,a+3=0a=-3,b=11/3 a^2 - (2b^2-(1/4 a^2-3b^2))= 1/3 a^2 - 2b^2 + (1/4 a^2-3b^2)= 1/3 a^2 - 2b^2 + 1/4 a^2 - 3b^2= (1/3+1/...