Since the line we are trying to study is parallel to the one given by the standard equation 5x + 3y = 6, it needs to have the same slope as this given line has. Let's write then this equation in slope-intercept so we can find what the slope is :
Then the slope of our line must also be "-5/3" in order to be parallel to the given line.
Now, since we also know a point (3, -1) through which the new line should go, we use the point-slope form of a line:
Let and . The differential volume dV of the cylindrical shells is given by
Integrating this expression, we get
To determine the limits of integration, we equate the two functions to find their solutions and thus the limits:
We can clearly see that x = 0 is one of the solutions. For the other solution/limit, let's solve for x by first taking the square of the equation above:
or
Since we are rotating the functions around the y-axis, we are going to use the x = 25 solution as one of the limits. So the expression for the volume of revolution around the y-axis is