Worked examples
Two examples
Example 1
Write the equation of the line with slope 2 through the point (3, 1).
- Start with y = 2x + b. The point is on the line: 1 = 2 × 3 + b.
- 1 = 6 + b, so b = −5.
Answer: y = 2x − 5
Example 2
Write the equation of the line with slope −1 through (−2, 4).
- 4 = −1 × (−2) + b, so 4 = 2 + b, and b = 2.
Answer: y = −x + 2
Where this is taught: Lines on the Grid, “2. Point-slope form”
The drill
Ten problems
How many:
Type the right-hand side, like 2x - 5 (fractions like 3/4x are fine). Then press Check my answers at the bottom.Write each answer on the line. The answer key, with the reasoning, is on the last page.