Cogito
Algebra 1 · Chapter 4 · Lesson 5
Intercepts and Standard Form
Where the line meets each axis.
11 problems · about 22 minutes · A-CED.A.2, F-IF.C.7
What this lesson teaches
The student finds intercepts and converts between standard and slope-intercept form.
- Set y to zero for the x-intercept and x to zero for the y-intercept.
- Standard form hides the slope but makes intercepts quick.
- Both intercepts together are enough to draw the line.
Warm Up
Straightforward practice. Get the method working first.
4 problems2x + 5y = 10. x-intercept?
Answer 5
Why 5.
x + y = 7. x-intercept?
Answer 7
Why Set y = 0.
3x + y = 9. y-intercept?
Answer 9
Why Set x = 0.
3x + y = 9. x-intercept?
Answer 3
Why 3x = 9.
Build It Up
The same ideas with more to keep track of.
3 problemsy = 5x − 20. x-intercept?
Answer 4
Why 0 = 5x − 20.
y = 5x − 20. y-intercept?
Answer -20
Why That is b.
How many points are needed to draw a line?
Answer 2
Why Two.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
4 problems4x + 2y = 16. y-intercept?
Answer 8
Why 2y = 16.
Select every true statement about intercepts.
Answer At the x-intercept, y is zero.; In y = mx + b, the y-intercept is b.
Why A horizontal line may cross the x-axis never, or everywhere.
Crossing the x-Axis: 2x + 4y = 8. What is the x-intercept?
Answer 4
Why 4.
Crossing the y-Axis: Same equation. What is the y-intercept?
Answer 2
Why 2.