Why can I not use the washer method? y=x^2, y=2x, rotated about the y-axis Reddit r/calculus

Take the region bounded by y=x^2 and y=2x and rotate it about the y-axis. Can we use the washer method? Or do we really have to use the shell method? Understand the washer method and the shell method by using a roll of toilet paper: https://youtu.be/I8sPRHRdCng?si=cJeq1HcpXYhl4-p2 Reddit r/calculus: https://www.reddit.com/r/calculus/s/SigRdICof7 ----------------------------- Support this channel and get my calculus notes on Patreon: 👉 https://www.patreon.com/blackpenredpen Get the coolest math shirts from my Amazon store 👉 https://amzn.to/3qBeuw6 ----------------------------- #calculus #bprpcalculus #apcalculus #tutorial #math