实数a,b互为相反数,c,d互为倒数,X的绝对值为根号7

a,b互为相反数,则a+b=0
c,d互为倒数,则c*d=1
X的绝对值为根号7,则x^2=7
x^2+(a+b+cd)x+(√(a+b)+cd的立方根)
=x^2+x+1
=8+x
=8±√7