Warm-Up Write the equation of a line in slope intercept form that has a slope of -3 and a y-intercept of 2. Write the equation of a line in slope intercept form that has a slope of 2 and a y-intercept of -5 Find the slope and y-intercept of the following:

Standard Form of an Equation Unit 4B Day 1 Standard Form of an Equation

Standard Form of an Equation Write the equation for STANDARD FORM: Ax + By = C A, B, and C must be whole numbers and A and B are both not zero

Change to Standard Form Examples of Standard Form 3x + 5y = 3 -2x + y = 7 2x − y =6 Equations Non-Examples x = 6 − y y = 2x + 7 2y = 4x +2

When is Standard Form useful? When you want to graph the line When you want to know the y-intercept of the line When you want to know the x-intercept Writing equations. y-intercept – the y value of the point where the line crosses the y-axis x-intercept – the x value of the point where the line crosses the x-axis

Examples Change each equation into Standard Form: 2y = 4x – 6 x + 7 = ½y x = -3y - 8

Try on your own: 4. 9x + 4 = -y 5. y = -5x + 1 6. ¼x – ¾y = -1

Find the y-intercept The y-intercept always occurs when x=___. To find the y-intercept of a line when the equation is in Ax + By = C, plug 0 into x in the equation and solve for the y value. This becomes the ordered pair for the y-intercept. (0, b)

Find the y-intercept 2x – y = -6 -2x + 4y = 12

On your own: 3. 7x – 14y = -56 4. -3x + 2y = 6

Find the x-intercept The x-intercept always occurs when y=___. To find the x-intercept of a line when the equation is in Ax + By = C, plug 0 into y in the equation and solve for the x value. This becomes the ordered pair for the x-intercept. (x, 0)

Find the x-intercept 2x – y = -6 -2x + 4y = 12

On your own: 3. 7x – 14y = -56 4. -3x + 2y = 6

Write the equation of the situation:

Classwork WS HW: 4.1