1.已知X^2+1/X^2=3,求X+1/x的值2.若|2A-5|与根号B+2互为相反数,求AB的值_数学解答

1.已知X^2+1/X^2=3,求X+1/x的值2.若|2A-5|与根号B+2互为相反数,求AB的值

人气：270 ℃　时间：2020-02-03 20:01:09

解答

设z^2=(x+1/x)^2=X^2+1/X^2+2=3+2=5
X+1/x=z=+根号5or-根号5
|2A-5|+根号B+2=0
所以2A-5=0 A=5/2
B+2=0 B=-2