Question

先化简再求值

[(x+3)/(x^2-9)]+[3/(x-3)]，其中x=-1

Answer 1

您好：
[(x+3)/(x^2-9)]+[3/(x-3)]
=（x+3）/(x+3)(x-3)+3/(x-3)
=1/(x-3)+3/(x-3)
=4/(x-3)
=4/(-1-3)
=4/(-4)
=-1

不明白，可以追问如有帮助，记得采纳，
谢谢 祝学习进步！

Answer 2

(x+3)/(x²-9)+3/(x-3)
=(x+3)/(x+3)(x-3)+3/(x-3)
=1/(x-3)+3/(x-3)
=4/(x-3)

当x=-1时
原式 = 4/(-1-3) = 4/(-4) = -1

Answer 3

[(x+3)/(x^2-9)]+[3/(x-3)]

=[(x+3)/(x+3)(x-3)]+3/([x-3)]
=1/([x-3)]+3/([x-3)]
=4/([x-3)]
代入x=-1得到
原式=4/（-1-3）=-1

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Answer 4

[(x+3)/(x^2-9)]+[3/(x-3)]=[1/(x-3)]+[3/(x-3)]=4/(x-3)，

当x=-1时，原式=-1。

Answer 5

如图