若mn互为相反数,ab互为倒数

Question

x=-(-4),求ab/2+（m+n）+x

Answer 1

mn互为相反数,ab互为倒数,x=-(-4),

m+n0
ab=1
x=4

ab/2+（m+n）+x
=1/2+0+4
=9/2

Answer 2

ab/2+（m+n）+x
=1/2+0+4
=4又1/2

Answer 3

mn互为相反数∴m+n=0
ab互为倒数 ∴ab=1
ab/2+（m+n）+x=1/2+0+4=9/2