Please, I really need help for tomorrow.

KristinDaBomb

New member
Joined
Apr 17, 2005
Messages
6
Here are the problems I need help with for tomorrow, thanks so much.

Find two ordered pairs of the solution: 2x+y=7

Find two ordered pairs of the solution: y-4x=-8

(-3, 7) and (-1, 3) This is supposed to be solved in x1 and x2 sort of form.

8x+y=-5 Solve that equation

Find the slope and y-intercept of y=5x-4 and y=1/5x-4 and tell if they are parallel

Find the slope and y-intercept of y=5x-4 and y=5x-1 and tell if they are parallel
 
You have to show some attempt at the problems before you post a laundry list like that.
 
happy said:
You have to show some attempt at the problems before you post a laundry list like that.

Ok.

2x+y=7 I got: (0, 2) and (0, 7) and that was wrong but I am not sure why

y-4x=-8 I got: (40, 4) and (0, -8)

(-3, 7) and (-1, 3) I got: 3-7 over -1+3= 4 over 2, which equals 2

8x+y=-5 I got: y=8x-5

y=5x-4 I got: Slope=5 and y-intercept= (0, -4)
y=1/5x-4 I got: Slope= 1 over 5 and y-intercept= (0, -4)

y=5x-4 I got: Slope=5 and y-intercept= (0, -4)
y=5x-1 I got: Slope=5 and y-intercept= (0, -4)
 
What Happy had in mind is how did you get your answers, not just what they are. But...

1) For 2x+y=7 the (0,7) works.
2*0+7 does = 7 but
2*0+2 does not = 7, it = 2 so it doesn't work.

2) y-4x=-8 I got: (40, 4) and (0, -8)
4-4*40 does not = -8, it is -154
-8-4(0) does = -8, it works.

3) Correct.

4) 8x+y=-5 I got: y=8x-5
Close. When you subtract 8x from both sides you get
8x-8x+y=-8x-5
Slope-intercepts are all good except for a typo in the last one. Look at again.
 
KristinDaBomb said:
1) Find two ordered-pair solutions for 2x+y=7
I got: (0, 2) and (0, 7)
How did you get y equalling 2 when x = 0? (Without being able to see your work, it's hard to say where you went wrong.)

KristinDaBomb said:
2) Find two ordered-pair solutions for y-4x=-8
Finding ordered-pair solutions is just a matter of picking x-values and plugging them in to find the corresponding y-values. So pick two different x-values, and do the plug-n-chug.

KristinDaBomb said:
3) (-3, 7) and (-1, 3)
This is supposed to be solved in x1 and x2 sort of form.
I'm sorry, but I don't know what that means...?

KristinDaBomb said:
I got: 3-7 over -1+3= 4 over 2, which equals 2
What were you doing to get this? It sort of looks like maybe the slope formula, but of course that doesn't work this way. Please reply with the actual instructions. Thank you.

KristinDaBomb said:
4) Solve 8x+y=-5
I got y=8x-5
So the instructions weren't "solve", but were "solve for y"...? If so, how did you move the "8x" to the other side without anything changing? Weren't you supposed to subtract it over?

KristinDaBomb said:
5) Find the slope and y-intercept of y=5x-4 and y=1/5x-4 and tell if the lines are parallel
y=5x-4 I got: Slope=5 and y-intercept= (0, -4)
y=1/5x-4 I got: Slope= 1 over 5 and y-intercept= (0, -4)
Yes. So what can you conclude about parallelism?

KristinDaBomb said:
6) Find the slope and y-intercept of y=5x-4 and y=5x-1 and tell if they are parallel
y=5x-4 I got: Slope=5 and y-intercept= (0, -4)
y=5x-1 I got: Slope=5 and y-intercept= (0, -4)
How did you get that second y-intercept point? And what did you conclude about parallelism?

Eliz.
 
stapel said:
KristinDaBomb said:
1) Find two ordered-pair solutions for 2x+y=7
I got: (0, 2) and (0, 7)
How did you get y equalling 2 when x = 0? (Without being able to see your work, it's hard to say where you went wrong.)

KristinDaBomb said:
2) Find two ordered-pair solutions for y-4x=-8
Finding ordered-pair solutions is just a matter of picking x-values and plugging them in to find the corresponding y-values. So pick two different x-values, and do the plug-n-chug.

KristinDaBomb said:
3) (-3, 7) and (-1, 3)
This is supposed to be solved in x1 and x2 sort of form.
I'm sorry, but I don't know what that means...?

KristinDaBomb said:
I got: 3-7 over -1+3= 4 over 2, which equals 2
What were you doing to get this? It sort of looks like maybe the slope formula, but of course that doesn't work this way. Please reply with the actual instructions. Thank you.

KristinDaBomb said:
4) Solve 8x+y=-5
I got y=8x-5
So the instructions weren't "solve", but were "solve for y"...? If so, how did you move the "8x" to the other side without anything changing? Weren't you supposed to subtract it over?

KristinDaBomb said:
5) Find the slope and y-intercept of y=5x-4 and y=1/5x-4 and tell if the lines are parallel
y=5x-4 I got: Slope=5 and y-intercept= (0, -4)
y=1/5x-4 I got: Slope= 1 over 5 and y-intercept= (0, -4)
Yes. So what can you conclude about parallelism?

KristinDaBomb said:
6) Find the slope and y-intercept of y=5x-4 and y=5x-1 and tell if they are parallel
y=5x-4 I got: Slope=5 and y-intercept= (0, -4)
y=5x-1 I got: Slope=5 and y-intercept= (0, -4)
How did you get that second y-intercept point? And what did you conclude about parallelism?

Eliz.


Thanks for the help guys.

I don't understand the ones where I have to find two ordered pairs, I have to graph it, so I still don't understand how to solve it to get them.

I understand #3.

I understand #4 now.

I don't understand what parallel means. That's why I can't solve it. And the second y-intercept I guessed. Thanks for all the help.
 
Ordered pairs: As staple said, you pick any value for x, then solve for the coresponding value of y. They make an ordered pair (x,y)
2x+y=7
x=-1:2(-1)+y=7:y=9:pair = (-1,9)
x=0: 2(0)+y=7:y=7: pair = (0,7)
x=1: 2(1)+y=7:y=5: pair = (1,5)
x=2: 2(2)+y=7:y=3: pair = (2,3)
They are all valid answers. They will all be on the graph of the line.
Parallel lines have the same slope.
 
Gene said:
Ordered pairs: As staple said, you pick any value for x, then solve for the coresponding value of y. They make an ordered pair (x,y)
2x+y=7
x=-1:2(-1)+y=7:y=9:pair = (-1,9)
x=0: 2(0)+y=7:y=7: pair = (0,7)
x=1: 2(1)+y=7:y=5: pair = (1,5)
x=2: 2(2)+y=7:y=3: pair = (2,3)
They are all valid answers. They will all be on the graph of the line.
Parallel lines have the same slope.

Thanks. :) I get that. I tried doing the second one.

y=2x-0 and got:

x=1: 2(1)-0= 2 Ordered Pair: (0, 2)
x=2: 2(2)-0= 4 Ordered Pair: (0, 4)

I don't think I did it right though.
 
KristinDaBomb said:
I tried doing the second one...and got:

x=1: 2(1)-0= 2 Ordered Pair: (0, 2)
If "x = 1", then why are you saying, in "(0, 2)", that x = 0?

KristinDaBomb said:
x=2: 2(2)-0= 4 Ordered Pair: (0, 4)
Does x = 2 or does x = 0? If you picked x = 2, then why are you giving the point as being (x, y) = (0, 4)?

Eliz.
 
stapel said:
KristinDaBomb said:
I tried doing the second one...and got:

x=1: 2(1)-0= 2 Ordered Pair: (0, 2)
If "x = 1", then why are you saying, in "(0, 2)", that x = 0?

KristinDaBomb said:
x=2: 2(2)-0= 4 Ordered Pair: (0, 4)
Does x = 2 or does x = 0? If you picked x = 2, then why are you giving the point as being (x, y) = (0, 4)?

Eliz.

Um I did it like:

x=1: 2(1) =2-0=2 so (0, 2)
x=2: 2(2) =4-0=4 so (0, 4)

But I see what you mean.

x=1: 2(1)=2-0=2 Ordered Pair: (1, 2)
x=2: 2(2)=4-0=4 Ordered Pairs (2, 4)

Is that right? Sorry for so many questions. I just started this math class and I'm new and missed alot of stuff.

I also still don't know if those are parallel. Anyone have anymore tips on getting the answer?
 
KristinDaBomb said:
I did it like:

x=1: 2(1)=2-0=2 Ordered Pair: (1, 2)
x=2: 2(2)=4-0=4 Ordered Pairs (2, 4)
I'm sorry, but which line is this? The equation you gave for (1) rearranges as "y = -2x + 7" and the equation for (2) rearranges as "y = 4x - 8". Where are you getting "y = 2x + 0"? (And why on earth did the book add a "plus zero" to the equation?)

Gene said:
Parallel lines have the same slope.
KristinDaBomb said:
I also still don't know if those are parallel.
Please review Gene's reply, wherein he answered this question.

Thank you.

Eliz.
 
Top