Slope-Intercept Form

1. Launch GrafEq by double clicking its icon. Click on the title screen to remove it.
2. Type in the equation y=Mx+B.
3. Press the Tab key, and assign a value to M by typing “M=1”.
4. Press the Tab key again, and assign a value to B by typing “B=0”. The input window is now complete.
5. Press the Return key to get the Create View window. The default mode (Cartesian) is correct, and the default bounds (-10 to 10) are fine for both x-axis and y-axis.
6. Click on the Create button. GrafEq will plot the graph of y=1*x+0.
7. The side-bar is currently showing general information. To display ticked axes:
   • click on the General button and drag the highlight bar to Ticks;
   • under the Simple submenu, click on the box with dense ticks and crosses;
   • click the Active checkbox to display the ticks and crosses.
   
8. Now, copy the graph onto the coordinate system graph paper. Label it “y=1*x+0”. Make a dot where the line crosses the y-axis and label it “0”. This point is called the y-intercept and its y-value is 0.
9. Next, change the value of B from 0 to -3:
   • click on the Ticks button and drag the highlight bar to General;
   • click on the Relation #1 button to display the relation entered;
   • click on the B=0 constraint, and change 0 to -3.
10. Repeat the necessary steps, as described above, to plot y=1*x+(-3). Label the new line on your graph paper as “y=x-3”. Q: What is the y-intercept of this line? Label the point where the line crosses the y-axis as “-3”.
11. Repeat the necessary steps for B=5. Q: What is the y-intercept of this line? Q: How should you label the y-intercept accordingly?
12. Q: Where will the line with equation y=x+7 cross the y-axis? Confirm your answer with GrafEq, by graphing y=x+7 (by setting B=7).
13. Q: Where do you think the graph of y=2x+5 will cross the y-axis? Confirm your answer with GrafEq, setting M=2 and B=5.
14. Now, in relation #1, set M=-4 and B=5.
15. Under the Graph menu, choose New Relation to get the Graph #1 Relation #2 input window.
16. Enter the equation y=0.2x+5. Press the Return key to see both Relation #2 and Relation #1 on Graph #1.
17. Repeat the necessary steps for the equation y=3x+5.
18. Q: What do the three lines have in common? Why?

Conclusion: