先化简再求值:x-1/x²-9÷(x/x-3-5x-1/x²-9),其中x=5.

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先化简再求值:x-1/x²-9÷(x/x-3-5x-1/x²-9),其中x=5.

x-1/x²-9÷(x/x-3-5x-1/x²-9)
=(x-1)/(x+3)(x-3) ÷ (x²+3x-5x+1)/(x+3)(x-3)
=(x-1)/(x-1)²
=1/(x-1)
=1/(5-1)
=1/4