已知:x²+3x+1=0,求下列各式的值:(1)x+(1\x);(2)x²\x的四次方+1
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已知:x²+3x+1=0,求下列各式的值:(1)x+(1\x);(2)x²\x的四次方+1
已知:x²+3x+1=0,求下列各式的值:(1)x+(1\x);(2)x²\x的四次方+1
已知:x²+3x+1=0,求下列各式的值:(1)x+(1\x);(2)x²\x的四次方+1
x^2+3x+1=0 -> x+1/x+3=0
(1) x+1/x=-3
(2) x^2/(x^4+1)=1/(x^2+1/x^2)
由(1)得 (x+1/x)^2=(-3)^2=9 -> x^2+1/x^2+2=9 -> x^2+1/x^2=7
所以x^2/(x^4+1)=1/7
因为x^2+3x+1=0
x+(1/x)+3=0
(1) x+(1/x)=-3