On a number line, numbers are marked at a distance of 1 cm apart from each other. One end of a line segment is at -8 and the other end is at 9. How long is the line segment (in cm)?

Options

A. 1
B. `-1`
C. 16
D. 17

Answer

To find the length of the line segment on a number line from -8 to 9, we can follow these steps:

### Step 1: Identify the endpoints of the line segment
The endpoints of the line segment are given as -8 and 9.

### Step 2: Use the formula for the length of a line segment
The length of a line segment between two points \( A \) and \( B \) on a number line can be calculated using the formula:
\[ \text{Length} = |B - A| \]
where \( A \) is the starting point and \( B \) is the ending point.

### Step 3: Substitute the values into the formula
Here, \( A = -8 \) and \( B = 9 \). Substituting these values into the formula gives:
\[ \text{Length} = |9 - (-8)| \]

### Step 4: Simplify the expression
Calculating the expression inside the absolute value:
\[ 9 - (-8) = 9 + 8 = 17 \]
Thus, we have:
\[ \text{Length} = |17| = 17 \]

### Step 5: State the final answer
Since the problem states that each unit on the number line corresponds to 1 cm, the length of the line segment is:
\[ \text{Length} = 17 \text{ cm} \]

### Final Answer:
The length of the line segment is **17 cm**.

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