#### 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