Final answer:
The expression for the difference between nine and the input is 9 - x, where x is the input value. Subtract a positive input directly, and add the absolute value of a negative input.
Step-by-step explanation:
The expression for the difference between nine and the input is 9 - x, where x represents the input value. If we think of the input as a variable in an equation, this expression translates to taking nine and subtracting the value of the input from it to find the difference. As in the examples provided, if your input is a positive number, such as +3, the expression would be calculated as 9 - (+3) = 9 - 3 = 6. Similarly, if the input is a negative number, like -6, the expression would be 9 - (-6), which simplifies to 9 + 6 = 15 because subtracting a negative is the same as adding the positive equivalent.