题目内容
(1)已知:a+b=3,x-y=1,求a2+2ab+b2-x+y的值.
(2)已知a-b=2005,ab=
,求a2b-ab2的值.
(2)已知a-b=2005,ab=
| 2008 |
| 2005 |
(1)∵a+b=3,x-y=1,
∴(a+b)2=a2+2ab+b2=9,
∴a2+2ab+b2-x+y
=9-1
=8.
(2)∵a-b=2005,ab=
,
∴a2b-ab2=ab(a-b)=
×2005=2008.
∴(a+b)2=a2+2ab+b2=9,
∴a2+2ab+b2-x+y
=9-1
=8.
(2)∵a-b=2005,ab=
| 2008 |
| 2005 |
∴a2b-ab2=ab(a-b)=
| 2008 |
| 2005 |
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