Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1.0 mm.
Conductor B is a hollow tube of outside diameter 2.0 mm and inside diameter 1.0 mm.
What is the resistance ratio Ra/Rb, measured between their ends??

Explanation:

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because it says use -2,0,and 2 for x, we can plug those numbers into the equation. y/4=3/4(-2)+2   y/4= -1 1/2 +2 now to get x by itself, we can multiply each side by 4. y=-6+8 which equals y=2 when x=-2. now you can do the same thing with 0 and 2 as x. you get y=8 when x=0 and y=14 when x=2.

x   |   y

-2 |   2

0   |   8

2   |   14