
如果x的二次方减去3X加上1等于o那么x的二次方加上x二次方分之一等于多少
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x^2 - 3x + 1 = 0
x^2 = 3x - 1
所以
x^2 + 1/x^2
= (x^4 + 1) / x^2
= ((3x-1)^2 + 1) / x^2
= (9x^2 - 6x + 2) / x^2
= (9x^2 - 2(3x - 1)) / x^2
= (9x^2 - 2x^2) / x^2
= 7.
x^2 = 3x - 1
所以
x^2 + 1/x^2
= (x^4 + 1) / x^2
= ((3x-1)^2 + 1) / x^2
= (9x^2 - 6x + 2) / x^2
= (9x^2 - 2(3x - 1)) / x^2
= (9x^2 - 2x^2) / x^2
= 7.
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