2x²+ax-y+6-2bx²+3x-5y-1=2(1-b)x²+(a+3)x-6y+5a=-3 b=1 (1/3)a³-2b²-（1/4）a²+3b²+2b²=(1/12)a³+3b²= (1/12)(-3)³+3*1²=-27/12+3=-9/4+12/4=3/4
