(2x 2+ax-y+6)-(2bx 2-3x+5y-1)=2x 2+ax-y+6-2bx 2+3x-5y+1=(2-2b)x 2+(a+3)x-6y+7,
因为它们的差与字母x的取值无关,所以2-2b=0,a+3=0,解得a=-3,b=1.
2(ab 2+2b 3-a 2b)+3a 2-(2a 2b-3ab 2-3a 2)
=6a 2-4a 2b+5ab 2+4b 3
=6×(-3) 2-4×(-3) 2×1+5×(-3)×1+4×1
=7.
(2x 2+ax-y+6)-(2bx 2-3x+5y-1)=2x 2+ax-y+6-2bx 2+3x-5y+1=(2-2b)x 2+(a+3)x-6y+7,
因为它们的差与字母x的取值无关,所以2-2b=0,a+3=0,解得a=-3,b=1.
2(ab 2+2b 3-a 2b)+3a 2-(2a 2b-3ab 2-3a 2)
=6a 2-4a 2b+5ab 2+4b 3
=6×(-3) 2-4×(-3) 2×1+5×(-3)×1+4×1
=7.