Transcript Y = mX + b - GetMoreMath
How do you find b?
How do you find b ?
How do you find
b
?
“DRY”
How do you find b (dry)?
Review What is slope-intercept form?
Y = mX + b ?
Review What is slope-intercept form?
Y = mX + b Input
Review What is slope-intercept form?
Y = mX + b ?
Review What is slope-intercept form?
Y = mX + b Output
Review What is slope-intercept form?
Y = mX + b ?
Review What is slope-intercept form?
Y = mX + b Rate of change a.k.a. Slope
Review What is slope-intercept form?
Y = mX + b ?
Review
How do you find b ?
What is slope-intercept form?
Y = mX + b Starting amount a.k.a. ‘y-intercept’
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
X Y
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
X Y 4 900
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
X 0 1 2 3 4 Y 900
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
X 0 1 2 3 4 Y 800 900
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
X 0 1 2 3 4 Y 700 800 900
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
X 0 1 2 3 4 Y 600 700 800 900
Riddle
b
I started with some money.
m
Every week I earned $100.
After 4 weeks, I had $900.
How much did I start with?
4 * 100
Gained $400
900 – 400
Started with $500 $500 X 0 1 2 3 4 Y 500 600 700 800 900
“DRY”
Write the equation of the linear relationship with:
m
m: 100 Y = mX + b
x y
point: (4, 900).
900 = 100(4) + b 900 = 400 + b – 400 –400 500 = b Y = 100X + 500
Ex. 1: Write the equation of a line that goes through (7, 8) and has a slope of 2. Y = mX + b Y = 2X – 6 NEED m and b NEED b!!!
How to use (7, 8)???
Input
X
Output
Y
Ex. 1: Write the equation of a line that goes through (7, 8) and has a slope of 2. Y = mX + b Y = 2X – 6 8 = 2 ( 7 ) + b 8 = 14 + b – 14 – 14 -6 = b How to use (7, 8)???
Input
X
Output
Y
Ex. 2: Write the equation of a line with this information: m slope: -5 X Y point: (-4, 3) Y = mX + b 3 is NOT y-intercept!!!
Ex. 2: Write the equation of a line with this information: m slope: -5 X Y point: (-4, 3) Y = -5X – 17 Y = mX + b 3 = -5 ( -4 ) + b 3 = 20 + b – 20 – 20 -17 = b
NEED m Ex. 3: Write the equation of a line that goes through (0, 8) and has a slope of 2. and b Y = mX + b Y = 2X + 8
NEED m Ex. 3: Write the equation of a line that goes through (0, 8) and has a slope of 2. and b Y = mX + b Y = 2X + 8
Ex. 4: Write a rule from this information: m X Y m: -4 point: (8, -2) Y = mX + b -2 = -4 ( 8 ) + b -2 = -32 + b + 32 + 32 30 = b Y = -4X + 30
Ex. 5: Write an equation for a relationship with this information: m: zero . point: (-4, -6) The change in y when x increases by one Y = -6
Ex. 6: Write an equation for a relationship with this information: m: undefined . point: (-4, -6) The change in y when x increases by one X = -4
The End