Question

若X=19/√19+8√3 则分式X^4-6X^3-2X^2+18X+23\X^2-8X+15

Answer 1

你这题显然,打错了已知条件

建议改为x=13/√(19+8√3)=13/√(4+√3)^2=13/(4+√3)=4-√3

4-x=√3

两边平方 x^2-8x+13=0

(X^4-6X^3-2X^2+18X+23)/(X^2-8X+15)

=x^2+2x-1-(20x-38)/(x^2-8x+13+2)

=x^2-8x+18

=x^2-8x+13+5

=5