Simplify: 1-(3/x) / 1-(9/x^2)?

2015-01-23 3:26 pm

回答 (1)

2015-01-23 3:34 pm
(1 - 3/x ) / ( 1-9/x^2)

1- 3/x = x/x - 3/x = (x-3)/x
1-9/x^2 = x^2/x^2 - 9/x^2 = (x^2-9) /x^2

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


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