ANSWER
[tex] {12}^{ - 2} [/tex]
EXPLANATION
The given expression is
[tex] \frac{1}{144} [/tex]
This is the same as:
[tex] \frac{1}{12 \times 12} [/tex]
In index notation, we write this as
[tex] \frac{1}{ {12}^{2} } [/tex]
To write this as a negative index, we use the property:
[tex] \frac{1}{ {a}^{m} } = {a}^{- m} [/tex]
This implies that;
[tex]\frac{1}{ {12}^{2} } = {12}^{ - 2} [/tex]