Slopeintercept Form Learn to write it Learn to

Slope-intercept Form Learn to write it Learn to graph using it Learn to rearrange equations to get it

y = mx + b This is used to graph a linear function WITHOUT having to use a table. You may rearrange an equation so that it is in this form. If you need to write an equation: your job is to do whatever it takes to find the actual numbers for m and b. IF you have the graph: count the slope, observe the yintercept

Ex. 1 Write an equation of the line whose slope is and whose y-intercept is – 6. Answer:

Ex. 2 Write an equation of the line whose slope is 4 and whose y-intercept is 3. Answer:

Ex. 3 Write an equation of the line shown in the graph. Answer: The equation of the line is

Ex. 4 Write an equation of the line shown in the graph. Answer:

Ex. 5 Graph Answer:

Standard Form Remember: Ax + By = C We want: y = mx + b Use the standard form to graph by graphing the x and y intercept (cover-up method). You may have to rearrange the equation to put it into slope-intercept form.

Ex. 6. Graph Answer:

Ex. 7 Graph Answer:

ex 8 Re-write the equation into slopeintercept form: x+y=3 Answer: y = -x + 3

Practice these: Write the equations in SIF: 1. x = y + 1 2. x + 4 y = 2 3. 2 x – 3 y = -5 4. 5 y = 8 – 4 x Answers: 1. y = x - 1 2. y = -1/4 x + ½ 3. y = 2/3 x + 5/3 4. y = 8/5 – 4/5 x

Health The ideal maximum heart rate for a 25 -yearold who is exercising to burn fat is 117 beats per minute. For every 5 years older than 25, that ideal rate drops 3 beats per minute. Write a linear equation to find the ideal maximum heart rate for anyone over 25 who is exercising to burn fat. Words The rate drops 3 beats per minute every 5 years, so the rate of change is beats per minute each year. The ideal maximum heart rate for a 25 -year-old is 117 beats per minute.

Variables Let R = the ideal heart rate. Let a = years older than 25. Equation Ideal rate equals R Answer: rate of change ideal rate years older for 25 times than 25 plus year-old. a 117

Graph the equation. The graph passes through (0, 117) with a slope of Answer:

Find the ideal maximum heart rate for a person exercising to burn fat who is 55 years old. The age 55 is 30 years older than 25. So, Ideal heart rate equation Replace a with 30. Simplify. Answer: The ideal heart rate for a 55 -yearold person is 99 beats per minute.

The amount of money spent on Christmas gifts has increased by an average of $150, 000 ($0. 15 million) per year since 1986. Consumers spent $3 million in 1986. a. Write a linear equation to find the average amount spent for any year since 1986. Answer: where D is the amount of money spent in millions of dollars, and n is the number of years since 1986

The amount of money spent on Christmas gifts has increased by an average of $150, 000 ($0. 15 million) per year since 1986. Consumers spent $3 million in 1986. b. Graph the equation. Answer:

The amount of money spent on Christmas gifts has increased by an average of $150, 000 ($0. 15 million) per year since 1986. Consumers spent $3 million in 1986. c. Find the amount spent by consumers in 1999. Answer: $4. 95 million