The domain of the function is \[A \ge0\] If A is negative we get an imaginary number for the radius. This makes sense because the area of a circle cannot be negative.
Y = 3X .............................
z = m - x
To solve for x, we can treat this like a typical algebraic problem.
We need to isolate x on one side.
<em><u>Add x to both sides</u></em>
z + x = m
<u><em>Subtract z from both sides</em></u>
x = m - z
This should be the answer.