Final answer:
To express the radical using the imaginary unit iii, the expression ± sqrt(-25) can be written as ± 5i.
Step-by-step explanation:
To express the radical using the imaginary unit iii, we need to rewrite the expression as a complex number. The expression ± sqrt(-25) can be written as ± sqrt(25 * -1), which simplifies to ± sqrt(25) * sqrt(-1). The square root of 25 is 5, so the expression becomes ± 5 * sqrt(-1).
The square root of -1 is denoted as i, so the final answer is ± 5i.