linear algebra question (slope intercept form vs standard form)

[ripple]

Was doing this question y=-5x + 9. Simple enough, just plugged in 0 for x and y and got the respective values but was wondering... isn't this in slope intercept form? Why don't we treat it as such? I did both, but the answer for standard form appeared to be the right one, now I am not sure when to answer such an equation in standard form vs slope intercept form! How can I tell?
Thanks

 

[Deleted member 4993]

Was doing this question y=-5x + 9. Simple enough, just plugged in 0 for x and y and got the respective values but was wondering... isn't this in slope intercept form? Why don't we treat it as such? I did both, but the answer for standard form appeared to be the right one, now I am not sure when to answer such an equation in standard form vs slope intercept form! How can I tell?
Thanks

As you described, those two processes should give you identical result. Please share your calculations, if you want to discuss (or catch) your mistake/s in calculation.

 

[HallsofIvy]

Was doing this question y=-5x + 9. Simple enough, just plugged in 0 for x and y and got the respective values but was wondering... isn't this in slope intercept form? Why don't we treat it as such? I did both, but the answer for standard form appeared to be the right one, now I am not sure when to answer such an equation in standard form vs slope intercept form! How can I tell?
Thanks

What question are you trying to answer? You say you "plugged in 0 for x and y and got the respective values" so I suspect you are trying to graph y= -5x+ 9. Setting x= 0 gives y= 9 so the graph goes through (0, 9). Setting y= 0 gives 0= -5x+ 9 and then x= 9/5 so the graph goes through (9/5, 0). The graph is the straight line through those points.

Using "slope-intercept" the slope is -5 and the intercept is (0, 9). Increasing x by 1 gives y= 9- 5= 4 (since the slope is -5) so another point on the graph is (1, 4). The graph is the line through (0, 9) and (1, 4). But since (1, 4) lies on the line through (0, 9) and (9, 4), this is the same graph as before.

 

[ripple]

ok, I will change the question in my clarification because I have done both answers for this one.

The questions states: Plot the linear functions by finding the x and y intercepts.

y=7x-3

My confusion is I am not sure if it wants me to graph in standard form or slope intercept form, the two give me 2 different answers.

Standard form: x intercept =(3/7, 0) and y intercept = (0, -3)

in slope intercept form though we get (0, -3) and (1, -4)

So not sure whether to solve for x and y as if its standard form or in slope intercept form as these give me different answers!

 

[ripple]

ah ok, I think i'm with you guys now, its same graph just slope intercept form another point is noted (a point that is there in standard form anyway).
My question would be then, would you guys approach that question from a slope-intercept format (go down 3, put 7 over 1 to get rise and run etc) or solve for x when y 0 and vise versa? I know its the same answer ultimately

 

[stapel]

The questions states: Plot the linear functions by finding the x and y intercepts.

y=7x-3

My confusion is I am not sure if it wants me to graph in standard form or slope intercept form, the two give me 2 different answers.

The "graph" is the drawing. It is not in any "form". It just "is".

Standard form: x intercept =(3/7, 0) and y intercept = (0, -3)

in slope intercept form though we get (0, -3) and (1, -4)

Since the second point does not have y=0, this cannot be the x-intercept.

Please reply showing the steps by which you started with plugging zero in for y, and ending up with y = 1. Thank you!

 

[JeffM]

You may have several sources of confusion.

Please explain what you mean by slope-intercept form and standard form.

And as was explained in the previous post, different forms of expressing the same mathematical relationship do not result in different graphs of that relationship.

Part of our difficulty in helping you is that you do not seem to have given us the exact and complete wording of the problem.