Question

已知实数a满足X^2-4x-1+=0,求X^2/x^2-4乘2+X/X^2-2X-1/X-2的值

Answer 1

你的公式中“/”号太多,猜的累

a^2-5a+1=0

a+1/a=5

a^2+1/a^2+2=25

a^2+1/a^2=23

1/6=1/8+1/u

1/u=8/48-6/48=2/48=1/24,u=24

(2-x)/(x-3)=k/(3-x)-2

(2-x)/(x-3)=(k-6+2x)/(x-3)

x≠3

2-x=k-6+2x,k=8-3x,x=3,k=-1时,会产生增根