已知实数m满足m²-3m+1=0,则代数式m²+[19/(m²+2)]的值为?
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m²-3m+1=0
m²=3m-1
m²+[19/(m²+2)]
=3m-1+19/(3m-1+2)
=3m-1+19/(3m+1)
=[(3m-1)(3m+1)+19]/(3m+1)
=(9m²-1+19)/(3m+1)
=(9m²+18)/(3m+1)
=(27m-9+18)/(3m+1)
=(27m+9)/(3m+1)
=9
m²=3m-1
m²+[19/(m²+2)]
=3m-1+19/(3m-1+2)
=3m-1+19/(3m+1)
=[(3m-1)(3m+1)+19]/(3m+1)
=(9m²-1+19)/(3m+1)
=(9m²+18)/(3m+1)
=(27m-9+18)/(3m+1)
=(27m+9)/(3m+1)
=9
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