Final answer:
The expression 15c⁻⁸ simplifies to 15/c⁸, by taking the reciprocal of c raised to the positive exponent while keeping the coefficient unchanged.
Step-by-step explanation:
To simplify the expression 15c⁻⁸ and write it using only positive exponents, we need to apply the rules of exponents. Specifically, a negative exponent indicates the reciprocal of the base raised to the positive exponent. Therefore, we can rewrite 15c⁻⁸ as 15/c⁸. In order to express it with only positive exponents, we would simply keep the coefficient as it is and take the reciprocal of c raised to the eighth power which is 15 times c to the power of -8 equals 15/c⁸ or, written in another way, 15 × c⁸.