Day Problems • Use the slope and y-intercept to graph each equation.

1. y = 2 – 3x 2. y = 2x + 5 3.

y

 3 4

x

 1 4.

y

  1 2

x

 3

• 6.3 Standard Form • Standard Form of a Linear Equation – The

standard form of a linear equation

is Ax + By = C, where A, B, and C are real numbers, and A and B are both not zero.

x – intercept –

the x-coordinate of the point where a line crosses the x-axis.

• To graph a linear equation in standard form, you can find the x-intercept by substituting 0 for y and solving for x.

• To find the y-intercept, substitute 0 for x and solve for y.

Finding x- and y-intercepts • Find the x- and y-intercept of 3x + 4y = 8. • Step 1 – to find the x-intercept, substitute 0 for y and solve for x.

3

x

 4

y

 8

3

x

 3

x

 8

x

 8 3 • So, the x-intercept is 8 .

3

Finding x- and y-intercepts • Find the x- and y-intercept of 3x + 4y = 8. • Step 2 – to find the y-intercept, substitute 0 for x and solve for y.

3

x

 4

y

 8 4

y y

 

8

8

y

 2 • So, the y-intercept is 2.

Graphing Lines Using Intercepts • Graph 2x + 3y = 12 using intercepts.

• Step 1 – Find the intercepts 2

x

 3

y

 12 Step 2 – Plot (6,0) 2

x

 3(0)  12 and (0,4). Draw a line through the points.

2

x x

 12  6

(0 , 4) (6 , 0)

2(0)  3

y

 12 3

y y

  12 4

Graphing Horizontal and Vertical Lines a. Graph y = -3.

b. Graph x = 2.

• Day Problems 2/9/11 Find the x- and y-intercepts of each equation.

1. x + 2y = 18 2. 3x – y = 9 3. -5x + y = 30 • Graph each equation using x- and y intercepts.

4. x + y = 2 5. -3x + y = 6

Transforming to Standard Form 2/9/11 • Write

y

 3 4

x

 2 in standard form using integers.

y

4 4

y



y

 3 4 

x

4     3 2 3 4

x x

4

y x

   8 8 2   

• Write the Equation in Standard Form

Write the equation in standard form using integers.

a. y = 3x + 1 -3x + y = 1 b.

y

 1 2

x

 4 2

y

8 2

y

 8

More Practice!!!

• Textbook – p. 301 #2 – 32 even.

• Homework – Worksheet 6.3