Page 35 - Math Course 1 (Book 2)

Linear Equations

Graph by Making a Table
To f nd the y-intercept, let x = 0.
Example
4x – y = 4 Original equation
Graph y = 2x + 2.
4(0) – y = 4 Replace x with 0.
Select values from the domain and make a table.
Then graph the ordered pairs. The domain is all –y = 4 Divide each side by –1.
real numbers, so there are inf nite solutions. Draw
a line through the points.
y = –4

x 2x + 2 y (x, y) Graph 4x – y = 4 using the x-intercept and y-intercept.
–2 2(–2) + 2 –2 (–2, –2)

–1 2(–1) + 2 0 (–1, 0)
0 2(0) + 2 2 (0, 2)

1 2(1) + 2 4 (1, 4)
2 2(2) + 2 6 (2, 6)

The x-intercept is 1, so the graph
intersects the x-axis at (1, 0). The
y-intercept is –4, so the graph
Answer
intersects the y-axis at (0, –4).
Answer Plot these points. Then draw a line
that connects them.

Your Turn!

Identify Linear Equations
Graph by Using Intercepts
Determine whether y = 4x – 5 is a linear equation.
If so, write the equation in standard form.
Example
a. linear equation; y = 4x – 5
Graph 4x – y = 4 using the x-intercept and the b. not a linear equation
y-intercept. c. linear equation; 4x – y = 5
d. linear equation; 4x + y = 5
To f nd the x-intercept, let y = 0. Answer

4x – y = 4 Original equation Determine whether 8y –xy = 7 is a linear equation.
If so, write the equation in standard form.
4x – 0 = 4 Replace y with 0.
a. not a linear equation
b. linear equation; 8y – xy = 7
4x = 4 Divide each side by 4. c. linear equation; 8y = 7 + xy
d. linear equation; 8y – 7 = xy
x = 1
Answer

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