问题
解答题
已知实数满足a2+3a-2=0，求
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答案
-1 a+1
×a+2 a2-1 a2-2a+1 a2+4a+4
=
-1 a+1
×a+2 (a-1)(a+1) (a-1) 2 (a+2) 2
=
-1 a+1 a-1 (a+1)(a+2)
=a+2-a+1 (a+1)(a+2)
=3 a 2+3a+2
∵a2+3a-2=0，
∴a2+3a=2，
∴原式=
=3 2+2
．3 4
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