please answer: 5/x 2 7/x-2 - 4/x2-4
回答 (3)
2008-08-11 4:12 pm
✔ 最佳答案
5/(x + 2) + 7/(x - 2) - 4/(x^2 - 4)= 5(x - 2)/(x + 2)(x - 2) + 7(x + 2)/(x + 2)(x - 2) - 4/(x + 2)(x - 2)
= (5x - 10)/(x + 2)(x - 2) + (7x + 14)/(x + 2)(x - 2) - 4/(x + 2)(x - 2)
= (5x - 10 + 7x + 14 - 4)/(x + 2)(x - 2)
= (5x + 7x - 10 + 10)/(x + 2)(x - 2)
= 12x/(x + 2)(x - 2)
2008-08-11 2:33 pm
= 5/(x + 2) + 7(x - 2) - 4/(x² - 4)
= 5/(x + 2) + 7/(x - 2) - 4/([x + 2][x - 2])
= (5x - 10 + 7x + 14 - 4)/([x + 2][x - 2])
= 12x/([x + 2][x - 2])
Answer: 12x/(x² - 4) or 12x/([x + 2][x - 2])
= 5/(x + 2) + 7/(x - 2) - 4/([x + 2][x - 2])
= (5x - 10 + 7x + 14 - 4)/([x + 2][x - 2])
= 12x/([x + 2][x - 2])
Answer: 12x/(x² - 4) or 12x/([x + 2][x - 2])
2008-08-11 2:49 pm
Having to GUESS question as :-
5 / (x + 2) + 7 / (x - 2) - 4 / (x² - 4)
5(x - 2) + 7 (x + 2) - 4
------------------------------
x² - 4
12 x
------------------
x² - 4
5 / (x + 2) + 7 / (x - 2) - 4 / (x² - 4)
5(x - 2) + 7 (x + 2) - 4
------------------------------
x² - 4
12 x
------------------
x² - 4
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