Question

一道数学题，帮忙解答解答，急急急！！！！

X²-3X+1=0(1)X²+1/X²=？（2）X²-1/X²=？（3）X³-4X²+4X+5=？
要分的话解答完了再给啊~~

Answer 1

x^2-3x+1=0
x+(1/x)-3=0
x+(1/x)=3

x^2+(1/x)^2=(1+1/x)^2-2=9-2=7
x^2-(1/x)^2=(x+1/x)^2-4=9-4=5
x^3-4x^2+4x+5
=x^3-4x^2-3x+1+7x+4
=x^3-4x^2-x^2+7x+4
=x^3-5x^2+7x+4
=x^3-3x^2-2x^2+7x+4
=x(x^2-3x)-2x^2+7x+4
=-2x^2+6x+4
=-2(x^2-3x)+4
=2+4
=6