When solved graphically, which system of equations will have exactly one point of intersection?

A) y=2x – 4
2y= 4x – 8

B) y=-x-10
y=-1/2x+10

C) y=-x-1
y = x + 1

D) y= 2/5x+3
y=.4x - 2

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

Ahiker stands at an unknown elevation before he ascends 2 miles up a mountain to an elevation of 9 miles. find the elevation of the hiker before his ascent.

Rectangle abcd is similar to rectangle rstu . what is the scale factor of a dilation from abcd to rstu ? enter your answer in the box.