Answer:
The index notation for 3x7x7x7x7 is: 
The index notation for 2x9x9x9x2x9 is: 
Step-by-step explanation:
Look at the numbers provided.
3×7×7×7×7 and 2×9×9×9×2×9
We aim to express the numbers in index notation.
Index notation serves as a concise method to represent repeated multiplication of the same value.
Examine the number.

In this instance, 3 appears once and 7 appears four times.
Thus, the index notation is: 
Now, for the second number.

Here, 2 occurs twice and 9 occurs four times.
Hence, the index notation is: 