Answer:
Slope is 3.5
There is a proportional relationship between the variables x and y
The other statements are false.
The slope is 3.5, not 7
A linear relationship is the same a proportional relationship so statement 4 is always false
The graph does pass through (0, 0)
Explanation:
Consider the first 2 pairs of coordinates, (2, 7) and (6, 21);
The increase in x is from 2 to 6, i.e. an addition of 4, the increase in y is from 7 to 21, i.e. an addition of 14;
Now consider the the 2nd and 3rd pairs of coordinates, (6, 21) and (8, 28);
The increase in x is from 6 to 8, i.e. an addition of 2, the increase in y is from 21 to 28, i.e. an addition of 7;
So, with the first 2 pairs of coordinates, an increase of 4 in x resulted in an increase of 14 in y and with the second 2 pairs of coordinates, an increase of 2 in x resulted in an increase of 7 in y, i.e. (+4, +14) and (+2, + 7);
2 × (+2, +7) = (+4, 14)
Or:
(+4, +14) ÷ 2 = (+2, +7)
This means a line from the 1st point to the 2nd point and a line from the 2nd point to the 3rd point will have the same gradient:
To find the slope simple, find the increase in y resulting from an increase of 1 in x, so:
(+2, +7) ÷ 2 = (+1, +3.5)
The gradient (or slope) is 3.5;
If there is a line with a fixed gradient that passes through all the points, then the relationship is proportional, also linear;
This is the case for this question;
If we follow the pattern backwards as well, so the point:
(2, 7) - (+2, +7) = (0,0)
This means (0,0) lies on the line.
(0,0), (2, 7), (4, 14), (6, 21), (8, 28), (10, 35), (12, 42), (14, 49), etc.
All these points would lie on the line, just add 2 to x, add 7 to y;
You would find the same points plus others by the rule, add 1 to x, add 3.5 to y.