The answer of my classmate that the line has a positive slope is CORRECT. This is because the line is most likely to lean to the right. The slope can be calculated through the equation,
slope = rise / run = change in y / change in x
If both are negative, the slope is POSITIVE.
Assume that the initial coordinates are (x,y) and that the dilated coordinates are (x',y').
The dilation is therefore:
(x,y) ............> (x',y')
Now, let's assume that the dilation factor is k.
Therefore:
x' = kx
y' = ky
Based on the above, all the student has to do is get the initial coordinates and the final ones and then substitute in any of the above two equations to get the value of k.
Example:
Assume an original point at (2,4) is dilated to coordinates (4,8). Find the dilation factor.
Assume the dilation coefficient is k.
(x,y) are (2,4) and (x',y') are (4,8)
Therefore:
x' = kx .........> 4 = k*2 ..........> k = 2
or:
y' = ky ..........> 8 = k*4 .........> k = 2
Based on the above, the dilation coefficient would be 2.
Hope this helps :)
-4x + y = 6
-5x - y = 21
add both of them
-9x = 27
x = -3
(-4*-3) + y = 6
-12 + y = 6
y = 18
Your answer will be :
the square root of 14, the square root of 54/3, 6.8, the square root of 26/3.
B = -16
m = (-15-(-16))/18-0 = 1/18
y= 1/18x - 16