How do I use substitution to find the solution of the system of equations #y=2x+1# and #2y=4x+2#?

Redirected from "How do I change #int_0^1int_0^sqrt(1-x^2)int_sqrt(x^2+y^2)^sqrt(2-x^2-y^2)xydzdydx# to cylindrical or spherical coordinates?"