Answer: 2m+m+m is really the same thing as saying m+m+m+m, or 4m. Use whatever you like as the expression :)
13=1/6y+2x
-1/6y -1/6y
-1/6y+13=2x
-13 -13
-1/6y=2x-13
*-6 *-6
y=-12x-13
*I multiply it by -6 because -6 is the reciprocal of -1/6, and I can't divide -1/6, actually I can, but it just going to be more confusing that way, and the fastest way to get rid of the -1/6 when you solving this type of equation is multiply it by its reciprocal.
When taking square roots, you can't take square roots of negative roots of negative numbers. So, what will work for the domain of u(x) is what makes u(x) zero or more. We can make an inequality for that.
u(x) ≥ 0.

9x + 27 ≥ 0 by squaring both sides
9x ≥ -27
x ≥ -3
So the domain of the function is when x ≥ -3 is true.
Answer:
The slope is defined as the ratio of the vertical change between two points, the rise, to the horizontal change between the same two points, the run.The vertical change between two points is called the rise, and the horizontal change is called the run.