1. The problem statement, all variables and given/known data y''+25y=cot(5x) Find one possible solution 3. The attempt at a solution I don't have any background in linear algebra, so I can't use cramers rule as a heads up, so I have to solve the system of equations (no linear algebra for this course is needed). Ok, so I take the auxiliary, r^2=-25, r=+/-5i y_h=Acos(5x)+Bsin(5x) y_1=cos(5x) y_2=sin(5x) Then, u_1'cos(5x)+u_2'sin(5x) = 0 -5u_1'sin(5x)+5u_2'cos(5x) = cot(5x) I am stumped at how to solve this system of equations. I think the rest before it is right..? Seems like the algebra has got me.