To write the expression 2 x 2 x 2 x 4 x 4 using exponents, we can first group the factors of 2 together, which gives:
(2 x 2 x 2) x 4 x 4
We can then write the group of three 2's as 2 raised to the third power (2^3), which gives:
2^3 x 4 x 4
Finally, we can simplify the expression by multiplying the two remaining factors of 4, which gives:
2^3 x 16
Therefore, the expression 2 x 2 x 2 x 4 x 4 written using exponents is 2^3 x 16.