What you’ll learn
Subtract rational numbers.
Key idea
Subtract a rational number by adding its opposite; two adjacent minus signs change the operation.
Subtract by adding the opposite; preserve minuend/subtrahend order and verify by adding the subtrahend back.
Worked example
Enter the exact value or ordered values in the format requested below.
Subtract (-9/2)-(-4/3). Enter the exact rational number.
- Subtracting (-4/3) means adding its opposite (4/3).
- (-9/2)+(4/3)=-19/6; adding the original subtrahend back gives -19/6+(-4/3)=-9/2.
Answer: -19/6
Quick Check
Evaluate a worked attempt at subtract rational numbers, identify the first invalid step, and provide the correction.
For (-9/2)-(4/3), Step 1 replaces subtraction with (-9/2)+(4/3)=-19/6, keeping the second sign unchanged. Locate the first invalid step and correct the difference.