Is my textbook wrong?

[TyranT]

Linear: Trying to place in the format of y=mx+c
m=3, (-4,-3)

I'm getting y=3x+5, Textbook says y=3x+9
Thanks

 

[MarkFL]

Hello, and welcome to FMH!

Did you check to see which equation, if either, contains the given point? I find your line doesn't but the textbook line does.

To derive the line, I would use the point-slope formula:

[MATH]y=3(x-(-4))+(-3)=3(x+4)-3=3x+12-3=3x+9\quad\checkmark[/MATH]

 

[JeffM]

Linear: Trying to place in the format of y=mx+c
m=3, (-4,-3)

I'm getting y=3x+5, Textbook says y=3x+9
Thanks

[MATH]y = mx + c \text { and} m = 3 \implies y = 3x + c.[/MATH]
[MATH]\therefore -\ 3 = 3(-\ 4) + c \implies - \ 12 + c = -\ 3 \implies c = 12 - 3 = 9.[/MATH]
In the future, please remember that we cannot tell you how to avoid mistakes unless you show your work.

 

[Harry_the_cat]

My guess is you put in -4 for y and -3 for x, instead of the other way around.