Question

how do you write an equation for slope-intercept form?

Answer 1

y=mx+b

m is the slope and b is the y intercept

Answer 2

maxine is correct.

Answer 3

What would be (-1,-2) & (3, 4)?

Answer 4

You have to do it two seperate times.

Answer 5

Use your given points of (-1,-2) and (3,4) to find your slope via:
\[m=\frac{ \Delta y }{ \Delta x }\]
Then you plug in your m into the slope-intercept form equation, along with one set of your (x,y) points to calculate your y-intercept value "b." The last step is to write the equation with your slope and y-intercept plugged in.
\[y=mx+b\]

Answer 6

I wish this made sense.

Answer 7

So to get your slope you do:
\[m= \frac{ \Delta y}{ \Delta x}=\frac{ y_2-y_1 }{ x_2-x_1 }\frac{ 4-(-2) }{ 3-(-1) }\]

Answer 8

wouldn't it be 2/4?

Answer 9

No, dont forget the negatives will turn it into a positive, so you'd get.
\[\frac{ 4-(-2) }{ 3-(-1) }=\frac{ 4+2 }{ 3+1 }=\frac{ 6 }{ 4 }\]

Answer 10

So we have that \[m=\frac{ 6 }{ 4 } \]
Our points are (-1,-2) and (3,4) so we can pick either set one or two to find out y-intercept. I'll pick point (3,4).
\[y=mx+b \rightarrow (4)=\frac{ 6 }{ 4 }(3)+b\]
Now you solve for "b", our y-intercept.

Answer 11

So to solve for b
\[4=\frac{ 6 }{ 4 }(3)+b \rightarrow 4=\frac{ 18 }{ 4 }+b \rightarrow b=4-\frac{ 18 }{ 4 } \rightarrow b=\frac{ 16 }{ 4 }-\frac{ 18 }{ 4 }\rightarrow b=-\frac{ 1 }{ 2 }\]

So now we end with
\[y=mx+b \rightarrow y=\frac{ 3 }{ 2 }x-\frac{ 1 }{ 2 }\]

I simplified our slope of 6/4 into 3/2, but it's the same thing.