# Need help with this question.Watch

#1

I answered part a correctly (I think) with the equation being y=7/2x+12.5, but I'm stuck with the final question. Is the y-axis the same for both points, because it says they meet here for A and B? If so (or not), what is the next step(s)? Please help, thanks.
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1 week ago
#2
(Original post by Tmoulti89)

I answered part a correctly (I think) with the equation being y=7/2x+12.5, but I'm stuck with the final question. Is the y-axis the same for both points, because it says they meet here for A and B? If so (or not), what is the next step(s)? Please help, thanks.
Here's a diagram:

https://www.desmos.com/calculator/tisqvgh3hf

You need to find where the lines cross the y-axis and then find the distance between those points. Does that help?
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#3
(Original post by Sir Cumference)
Here's a diagram:

https://www.desmos.com/calculator/tisqvgh3hf

You need to find where the lines cross the y-axis and then find the distance between those points. Does that help?
Thank you. Yes, that makes it clearer now but how do I find where they cross the y-axis?
0
1 week ago
#4
(Original post by Tmoulti89)
Thank you. Yes, that makes it clearer now but how do I find where they cross the y-axis?
Lines cross the y-axis at points where the x-coordinate is 0 e.g. points like (0,3) or (0,-2). So if you substitute x = 0 into each equation it will give you the y-intercepts.

Or if you're familiar with y = mx + c then "c" is the y-intercept.
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#5
(Original post by Sir Cumference)
Lines cross the y-axis at points where the x-coordinate is 0 e.g. points like (0,3) or (0,-2). So if you substitute x = 0 into each equation it will give you the y-intercepts.

Or if you're familiar with y = mx + c then "c" is the y-intercept.
Ok, so I found the y intercepts to be -7 and 12.5. Do I need to use the (square root)(x1-x2)squared + (y1-y2)squared formula?
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1 week ago
#6
(Original post by Tmoulti89)
Ok, so I found the y intercepts to be -7 and 12.5. Do I need to use the (square root)(x1-x2)squared + (y1-y2)squared formula?
No, look at the diagram that I linked to above. You know that the top line crosses the y-axis at 12.5 and the bottom line crosses at -7. Can you use the diagram to work out the distance between the points? Don't think about any formulae - just think about how to find the distance.
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#7
(Original post by Sir Cumference)
No, look at the diagram that I linked to above. You know that the top line crosses the y-axis at 12.5 and the bottom line crosses at -7. Can you use the diagram to work out the distance between the points? Don't think about any formulae - just think about how to find the distance.
Subtract them?
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1 week ago
#8
(Original post by Tmoulti89)
Subtract them?
Yes as long as you do it in the right order. I'm still not sure if you're guessing or actually considering the graph. Have a look at this new diagram:

https://www.desmos.com/calculator/ld956artdp

What's the distance between A and B? It should really be clear without you having to guess a method. You can even count the squares if you like.
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#9
(Original post by Sir Cumference)
Yes as long as you do it in the right order. I'm still not sure if you're guessing or actually considering the graph. Have a look at this new diagram:

https://www.desmos.com/calculator/ld956artdp

What's the distance between A and B? It should really be clear without you having to guess a method. You can even count the squares if you like.
Ah, I see now. So the answer is 19.5.
1
1 week ago
#10
(Original post by Tmoulti89)
Ah, I see now. So the answer is 19.5.
Correct
1
#11
(Original post by Sir Cumference)
Correct
Thank you so much for all your help. I really appreciate it.
0
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