graph

OP

Original post by mqb2766

For the equation of the lines, you'd be expected to work out what "m" and "c" for each line.
If they meet (they do), put the coordinates of the point where they meet.

How do I work out the gradient?

Reply 4

Original post by jqhsehs

How do I work out the gradient?

(change in y) / (change in x)

If you move along 4 (x) and up one (y), the gradient is 1/4. Try for these two lines?

Reply 5

OP

Original post by mqb2766

(change in y) / (change in x)

If you move along 4 (x) and up one (y), the gradient is 1/4. Try for these two lines?

Does it have to be only up one for y?

Reply 6

Original post by jqhsehs

Does it have to be only up one for y?

You must have a book with this in, or just a quick google for the equation of a line.
Pick a point on the line, then move to another point on the line. Count how many you've gone along (x) and how many you've gone up (y).

Reply 7

OP

Original post by mqb2766

You must have a book with this in, or just a quick google for the equation of a line.
Pick a point on the line, then move to another point on the line. Count how many you've gone along (x) and how many you've gone up (y).

But, there's so many different points you can pick won't that mean the gradient could be wrong or something...

Reply 8

Original post by jqhsehs

But, there's so many different points you can pick won't that mean the gradient could be wrong or something...

Whichever two points you pick, "m" is a constant so it does not change. That is what a line is.
Pick two points which make counting the changes in x and y as easy as possible.

Reply 9

OP

Original post by mqb2766

Whichever two points you pick, "m" is a constant so it does not change. That is what a line is.
Pick two points which make counting the changes in x and y as easy as possible.

would this be correct - y=2.5x+-1

Reply 10

Original post by jqhsehs

would this be correct - y=2.5x+-1

Neither line is of that form. If you want to check yourself, put a few values of x into the equation and see what they evaluate to (do they lie on the line)?
Pls show how you came up with those numbers?

Reply 11

OP

Original post by mqb2766

Neither line is of that form. If you want to check yourself, put a few values of x into the equation and see what they evaluate to (do they lie on the line)?
Pls show how you came up with those numbers?

I went along 2 on the x axes and up 5 on the y axes then divided them

Reply 12

Original post by jqhsehs

I went along 2 on the x axes and up 5 on the y axes then divided them

Look at the scales on the x and y axes, don't just count boxes.
Also, did you go up 4 rather than 5?

Reply 13

OP

Original post by mqb2766

Look at the scales on the x and y axes, don't just count boxes.
Also, did you go up 4 rather than 5?

would the answer be
y=2x+-1
y= -0.5x+-1 ?

Reply 14

Original post by jqhsehs

would the answer be
y=2x+-1
y= -0.5x+-1 ?

Gradients look good this time. Not sure about the constants though, what is +-1?
If you're unsure, put x = 0. What are the values of y, are they the same on the graph?

Reply 15

OP