To determine which of the given rational numbers can be expressed as a repeating decimal, we need to consider their denominator when expressed in simplest form. A rational number will have a repeating decimal if, when reduced to its simplest form, the denominator has prime factors other than 2 and 5.
- 78: It's a whole number, so it can be expressed as a decimal: 78.0 (terminating).
- 512: It's also a whole number: 512.0 (terminating).
- 1725: Again, it's a whole number: 1725.0 (terminating).
- 3140: Yet another whole number: 3140.0 (terminating).
None of the above whole numbers have a denominator after simplification, so they are not expressed as repeating decimals.
Since all provided options are integers and thus will convert to terminating decimals in decimal form, none of these numbers are repeating decimals.
The answer is none of the options listed can be expressed as a repeating decimal; all are terminating when expressed in decimal form.