Let’s solve each system of linear equations by graphing. Since we’re solving by graphing, we’ll find where the two lines intersect — that point (x, y) is the solution.
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Problem 1:
Equations:
- \( y = -\frac{4}{5}x + 5 \)
- \( y = 1 \)
The second equation is a horizontal line at y = 1.
To find the intersection, plug y = 1 into the first equation:
\( 1 = -\frac{4}{5}x + 5 \)
Subtract 5 from both sides:
\( 1 - 5 = -\frac{4}{5}x \)
→ \( -4 = -\frac{4}{5}x \)
Multiply both sides by 5 to eliminate denominator:
→ \( -20 = -4x \)
Divide both sides by -4:
→ \( x = 5 \)
So the solution is
(5, 1)
✔ Check: Plug x=5 into first equation → y = -4/5 * 5 + 5 = -4 + 5 = 1 ✔️
Second equation: y=1 ✔️
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Problem 2:
Equations:
- \( y = \frac{1}{4}x + 2 \)
- \( y = x - 1 \)
Set them equal since both equal y:
\( \frac{1}{4}x + 2 = x - 1 \)
Subtract \( \frac{1}{4}x \) from both sides:
→ \( 2 = \frac{3}{4}x - 1 \)
Add 1 to both sides:
→ \( 3 = \frac{3}{4}x \)
Multiply both sides by 4:
→ \( 12 = 3x \)
Divide by 3:
→ \( x = 4 \)
Now plug x=4 into either equation to get y. Use second one: y = 4 - 1 = 3
Solution:
(4, 3)
✔ Check in first equation: y = (1/4)(4) + 2 = 1 + 2 = 3 ✔️
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Problem 3:
Equations:
- \( y = -\frac{8}{3}x + 3 \)
- \( y = -\frac{4}{3}x - 1 \)
Set equal:
\( -\frac{8}{3}x + 3 = -\frac{4}{3}x - 1 \)
Add \( \frac{8}{3}x \) to both sides:
→ \( 3 = \frac{4}{3}x - 1 \)
Add 1 to both sides:
→ \( 4 = \frac{4}{3}x \)
Multiply both sides by 3:
→ \( 12 = 4x \)
Divide by 4:
→ \( x = 3 \)
Plug x=3 into second equation: y = -4/3 * 3 - 1 = -4 - 1 = -5
Solution:
(3, -5)
✔ Check in first equation: y = -8/3 * 3 + 3 = -8 + 3 = -5 ✔️
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Problem 4:
Equations:
- \( y = -3 \)
- \( y = \frac{1}{4}x - 2 \)
First equation is horizontal line at y = -3.
Plug y = -3 into second equation:
→ \( -3 = \frac{1}{4}x - 2 \)
Add 2 to both sides:
→ \( -1 = \frac{1}{4}x \)
Multiply both sides by 4:
→ \( x = -4 \)
Solution:
(-4, -3)
✔ Check: Plug x=-4 into second equation → y = (1/4)(-4) - 2 = -1 - 2 = -3 ✔️
First equation: y=-3 ✔️
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Final Answer:
1. (5, 1)
2. (4, 3)
3. (3, -5)
4. (-4, -3)
Parent Tip: Review the logic above to help your child master the concept of worksheet solving systems of equations by graphing.