areyouready2007
幼苗
共回答了20个问题采纳率:95% 举报
a² + 4a - 5 = 0
( a + 5 )( a - 1 ) = 0
∴ a = - 5 或 a = 1
① 1 / ( a + 1 ) - ( a + 3 ) / a² - ( 1 × a² - 2a + 1 ) / ( a² + 6a + 9 )
= 1 / ( a + 1 ) - ( a + 3 ) / a² - ( a - 1 )² / ( a + 3 )²
当 a = - 5 时,原式= - 917 / 100
当 a = 1 时,原式= - 7 / 2
② 1 / ( a + 1 ) - ( a + 3 ) / ( a² - 1 × a² - 2 a ) + 1 / ( a² + 6a + 9 )
= 1 / ( a + 1 ) - ( a + 3 ) / ( 2a ) + 1 / ( a + 3 )²
当 a = - 5 时,原式= 1 / 5
当 a = 1 时,原式= 41 / 16
1年前
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