Answer:
a) [tex]-\frac{21}{18}[/tex], b) [tex]\frac{2}{8}[/tex].
Step-by-step explanation:
Let be [tex]u[/tex] a real number, its additive inverse is a real number [tex]v[/tex] so that:
[tex]u+v = 0[/tex]
That is,
[tex]v = - u[/tex] (1)
Then, the additive inverses of [tex]\frac{21}{18}[/tex] and [tex]-\frac{2}{8}[/tex] are, respectively:
a) [tex]-\frac{21}{18}[/tex], b) [tex]\frac{2}{8}[/tex].