You're working on
Unit 3: Lesson 8 – Standard Form, where you need to find the
x-intercept and
y-intercept of each linear equation (in standard form: Ax + By = C), and then graph the line using those two points.
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🔑 Key Concept:
- The
x-intercept is where the line crosses the x-axis →
y = 0
- The
y-intercept is where the line crosses the y-axis →
x = 0
So for any equation in standard form, plug in y=0 to find x-intercept, and x=0 to find y-intercept.
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Let’s solve each one step by step:
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✔ 1) x + 2y = 8
x-intercept (set y = 0):
x + 2(0) = 8 → x = 8
→
x-int = (8, 0)
y-intercept (set x = 0):
0 + 2y = 8 → y = 4
→
y-int = (0, 4)
✔ Fill in:
x-int =
8
y-int =
4
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✔ 2) 3x - y = 9
x-intercept (set y = 0):
3x - 0 = 9 → 3x = 9 → x = 3
→
x-int = (3, 0)
y-intercept (set x = 0):
0 - y = 9 → -y = 9 → y = -9
→
y-int = (0, -9)
✔ Fill in:
x-int =
3
y-int =
-9
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✔ 3) -5x + 6y = 30
x-intercept (set y = 0):
-5x + 0 = 30 → -5x = 30 → x = -6
→
x-int = (-6, 0)
y-intercept (set x = 0):
0 + 6y = 30 → y = 5
→
y-int = (0, 5)
✔ Fill in:
x-int =
-6
y-int =
5
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✔ 4) 4x + 3y = -9
x-intercept (set y = 0):
4x + 0 = -9 → x = -9/4 =
-2.25
→
x-int = (-2.25, 0)
y-intercept (set x = 0):
0 + 3y = -9 → y = -3
→
y-int = (0, -3)
✔ Fill in:
x-int =
-2.25 or
-9/4
y-int =
-3
*(Note: You can write as fraction or decimal — both are acceptable unless specified.)*
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✔ 5) -3x + y = 6
x-intercept (set y = 0):
-3x + 0 = 6 → -3x = 6 → x = -2
→
x-int = (-2, 0)
y-intercept (set x = 0):
0 + y = 6 → y = 6
→
y-int = (0, 6)
✔ Fill in:
x-int =
-2
y-int =
6
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✔ 6) 5x - 3y = 15
x-intercept (set y = 0):
5x - 0 = 15 → x = 3
→
x-int = (3, 0)
y-intercept (set x = 0):
0 - 3y = 15 → -3y = 15 → y = -5
→
y-int = (0, -5)
✔ Fill in:
x-int =
3
y-int =
-5
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## 📊 How to Graph Each Line:
Once you have the x- and y-intercepts:
1. Plot the
x-intercept point on the x-axis.
2. Plot the
y-intercept point on the y-axis.
3. Draw a straight line connecting the two points.
Example for #1: Plot (8,0) and (0,4), draw line through them.
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## ✍️ Final Answers to Fill In:
1) x-int =
8, y-int =
4
2) x-int =
3, y-int =
-9
3) x-int =
-6, y-int =
5
4) x-int =
-2.25 (or -9/4), y-int =
-3
5) x-int =
-2, y-int =
6
6) x-int =
3, y-int =
-5
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📌
Pro Tip: Always double-check your intercepts by plugging them back into the original equation!
Let me know if you want help graphing any of these lines! 😊
Parent Tip: Review the logic above to help your child master the concept of standard form equation worksheet.