for example, https://www.wolframalpha.com/input/?i=volume+of+revolved+solid+of+region+bounded+by+y+%3D+-2x+%2B+1+%2C+y+%3D+5%2C+x+%3D+0+about+the+x+axis
doesn't give a definite value of the answer to the question, why is that?
On the other hand, the same question, except rotating along y axis, gives an answer: https://www.wolframalpha.com/input/?i=volume+of+revolved+solid+of+region+bounded+by+y+%3D+-2x+%2B+1+%2C+y+%3D+5%2C+x+%3D+0+about+the+y+axis
This is creating difficulties, and any help is deeply appreciated.
