I need help with this please! I want someone to go through the steps with me, not tell me the answer. Thanks~! ^_^

Choose the equation that represents the graph below:

Question

I need help with this please! I want someone to go through the steps with me, not tell me the answer. Thanks~! ^_^ 

Choose the equation that represents the graph below:

yato_gami · Answer

attachment

yato_gami · Answer

A. y = −2x − 4

 B. y = 2x + 4

 C. y = −2x + 4

 D. y = 2x − 4

welshfella · Answer

Hint: equations with a negative slope ( like \)   have a negative coefficient of x.

welshfella · Answer

the general form of equation of a straight line is 
y = mx + b  
where  m = slope and b = value of y where the line intersects the y-axis.

yato_gami · Answer

Alright, got it so far.

yato_gami · Answer

So the slope is going to be negative right?

welshfella · Answer

OK so this should lead you to the correct option
check out the graphs 

Yes

welshfella · Answer

the slope = rise / run

|dw:1482324219035:dw|

3mar · Answer

It is also an easy equation and you will be familiar with it so more..

Plotting a line using two points:
- At least two points of (x,y) are sufficient to plot a straight line.
- Select the easiest points from the graph through the m the line passes.

welshfella · Answer

yes to get value of rise / run in this case select points where the graph passes throught the axes

3mar · Answer

After you have picked two points, you would use this formula to form he equation of this line.

You would choose the two-points formula!

yato_gami · Answer

So I just pick any two points on the graph?

3mar · Answer

yes, any two points through them the line passes.
In other words, it is not logic to pick (4,4) for example!!!
instead you would pick (2,-8)

3mar · Answer

Time for pray - 25 min

3mar · Answer

I think this would help you.

3mar · Answer

@welshfella 
If you don't mind, take it until I pray...
Thanks in advance.

3mar · Answer

Sorry @Yato_Gami
The electricity was off twice..

mathmale · Answer

Try this:

Determine, just from looking at the graph, where the line crosses the y-axis.  This point is called the "y-intercept" and in this case is (0,-2).  
Next, determine the slope of the line from inspection.  yes, you could choose any two points that lie on the graph, but it'd be easiest to choose (-2,0) and (0,-4).  Why?  Because the line goes thru those two points exactly.  From the looks of the graph, you can see immediately that the function is decreasing as x increases, so can assume immediately that the slope is negative.  What is the slope?  m  =   "rise"   over   run.

Write the slope-intercept form of the equation of the line:  y=mx+b.