Comprehensive Calculator Guide
This calculator finds the constant k in a direct proportion y = kx from a table of values, and checks whether the relation is proportional at all by working out y ÷ x for each pair. Tomatoes at SAR 3.5 a kilo are proportional; a taxi fare with a starting fee is not.
Direct proportion
y ÷ x is the same for every pair; its graph is a line through the origin with slope k. A linear relation with a constant term, like a taxi fare of 2x + 9, isn’t proportional.
How to Use
- Enter the x values.
- Enter the matching y values.
- Press “Check” to see whether it is proportional and k.
Formula Used
k = y ÷ x, equal for every pair
Practical Examples
- Example 1
- Tomatoes: k = 3.5.
- Example 2
- Taxi: not proportional; y = 2x + 9.
Important Tips
- Divide y by x.
- The line must pass the origin.
- Use y = kx for unknowns.
Common Mistakes to Avoid
- Judging from two pairs.
- Calling every line proportional.
- Dividing x by y.
Frequently Asked Questions
- What is k?
- The fixed ratio y ÷ x.
- Is my table proportional?
- If every y ÷ x matches.
- Every line?
- Only through the origin.