I am soooo confused about this:

How can you tell if a slope is negative or positive? For instance in this question (btw I know what to fill in the second blank):

How can I tell? I NEED A SIMPLE EXPLANATION IM DUMB.

ISmellGood
Sep 2, 2017

#1**0 **

If the line is going up, it's positive. If the line is going down, it's negative.

That's probably the simplest answer...

Gh0sty15
Sep 2, 2017

#3**+1 **

Ghosty, do you really think your answer makes sense.

All lines that are not horizontal or vertical go up on one end and down on the other end ://

Melody
Sep 2, 2017

#10**+2 **

My brain needs a few adjustments... Making too many mistakes in math. It might take a while for me to get back on track. Sorry everyone.

Gh0sty15
Sep 2, 2017

#2**+2 **

Hi,

Firstly you are not dumb, :)

Dumb people do not bother to ask good questions :)

First .. is the gradient positive or negative. ??

Lines go for ever, if you think about any line,

it may eventually be in the top right corner where the + is in which case the gradient will be positive.

OR

it will eventually be in the top left corner where the - is in which case the gradient will be negative.

So does your line have a positive or a negative gradient ?

Now, I think your line goes through the two points (0,-9) and (3,3)

Draw a right angled triangle between these two known points. One side has to be parallel to the x axis and the other parallel to the y axis, like I have done.

gradient is rise/run To get from the bottom point to the top one you have to rise 12 and run along 3

SO the gradient is + (because the line heads off to the top right corner) 12/3 = +4

The y intercept is -9, you said you already knew that.

b=-9

m=4

line: y=mx+b

this line y=4x+-9

** y=4x-9**

I have redrawn you graph so I can explain better

Melody
Sep 2, 2017

#4**+1 **

When the line looks like a backslash "\", its slope is negative.

When the line looks like a slash "/". it slope is positive.

MaxWong
Sep 2, 2017