1. Writing Linear Equations

2. Do I have m and y-intercept ? If m and y-intercept are given, simply substitute into the slope-intercept equation. Example: m = – 3, y-intercept (0, 5)

3. Do I have m and y-intercept ? *Remember your positive and negatives* Example:

4. Do I have m and a point ? If you only have m and a point, follow these steps. Step 1: using m and the point, substitute for y, m, and x in the equation, leaving b as the only unknown. Step 2: Solve for b. Step 3: Now you have m and b, write the equation in y = m (x) + b form.

5. Example Substitute and get:

6. Solve for b So,

7. What if I only two points? *Remember: slope (m) is the change in y over the change in x. Step 1: define change as ‘the difference’ between the y values and x values. Step 2: use this equation to solve for m. *It is very important to make sure what point you define as (x 1, y 1 ) and which point is (x 2, y 2 ). ORDER MATTERS!*

8. Then what? Now that you have a slope, and two points, use the slope, and just ONE of the points. Step 1: substitute one of the (x, y) and the m, to find b. Step 2: use m and b to write the linear equation.

9. Example Start by finding m.

10. Example, cont… Let’s use m, and point C.

11. Example, cont… The linear equation is:

12. Example 2 Start by finding m.

13. Example 2, cont… Let’s use m, and point K.

14. Example 2, cont… The linear equation is:

15. Extra Help or Practice Interactive practice on graphing linear equations Interactive practice on graphing linear equations How to write linear equations given different pieces How to write linear equations given different pieces Tutorials on writing linear equations.