Answer:
All options are correct.
Step-by-step explanation:
We have to find the expression which are in the simplest form.
A.[tex]x^{-3}+y^3[/tex]
The expression cannot solve further.
Therefore, the given expression is in the simplest form .
B.[tex]\frac{1}{x^4}[/tex]
The expression cannot solve further.
The given expression is in the simplest form.
C.[tex]\frac{w^7}{x^2}[/tex]
[tex]x^2[/tex] cannot divide [tex]w^7[/tex].
The expression cannot solve further.
Hence, the given expression is in the simplest form.
D.[tex]a^{-9}[/tex]
The expression cannot solve further.
The given expression is in the simplest form.
E.[tex]\frac{1}{a^2}+b^2[/tex]
The expression cannot solve further.
Hence, the given expression is in the simplest form.
F.[tex]\frac{1}{b^5}[/tex]
The expression cannot solve further.
Hence, the given expression is in the simplest form.
Hence, all options are true.