若A方-3A+1=0,求3A三次方-8A方+A+(A方+1)分之3

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若A方-3A+1=0,求3A三次方-8A方+A+(A方+1)分之3

若A方-3A+1=0,求3A三次方-8A方+A+(A方+1)分之3
若A方-3A+1=0,求3A三次方-8A方+A+(A方+1)分之3

若A方-3A+1=0,求3A三次方-8A方+A+(A方+1)分之3
a² - 3a + 1 = 0
a² - 3a = - 1
a² + 1 = 3a
同除以 a
a + 1/a = 3
3a³ - 8a² + a + 3/(a²+1)
= 3a³ - 9a² + a² + a + 3/(3a)
= 3a(a² - 3a) + a² + (a + 1/a)
= - 3a + a² + 3
= - 1 + 3
= 2