【第一份】:
⒈-a^8
⒉D
⒊D
⒋1 x³
⒌(x+2)(y+3)-(x+1)(y-2)
=xy+3x+2y+6-(xy-2x+y-2)
=5x+y+8
把x=-1,y=3代入,得:
=-5+3+8
=6.
⒍(2x+3y)(x-y)-(y+2x)(2x-y)
=2x²-2xy+3xy-3y²-(4x²-y²)
=-2x²+xy-2y².
【第二份】:
⒈a(b+2)(b-2)
⒊x²+1/x²=(x+1/x)²-2x•1/x=4-2=2
⒍9
⒏(x²+px+8)(x²-3x+q)
=x^4-3x³+qx²+px³-3px²+pqx+8x²-24x+8q
=x^4+(p-3)x³+(q-3p+8)x²+(pq-24)x+8q
∵不含x²与x³的项,
∴q-3p+8=0,
p-3=0,
解得p=3,q=1.
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