I have corrected the mistake. Thanks a lot for the feedback guys.

Thanks Alex. That took care of that one. I am running into a problem on this next equation: y''+.01y'+4y=2cos(2t), y(0)=y'(0)=0,t=0..10. I am recieving this: Error, attempting to assign to `plot` which is protected. Here is how I am entering it. e4:=diff(y(t),t,t)+diff(y(t),t)*.01+y(t)*4=2*cos(2t); S4:=dsolve([e4,y(0)=0,y'(0)=0]); r4:=rhs(s4); plot(r4,t=0..10); Any thoughts?

Thanks again guys for the help. The tips have been extremely useful, however I am yet to successfully graph the 4th equation. I have tried Alex's way, but the plot shows up empty. Any tips?

Thanks a lot for the help David. However, I am still recieving an error saying empty plot when I try to plot with DEplot. Why is this? Thanks again for the feedback.

dx/dt=x^2+a^2, a is greater than 0 and less than 1. (the greater and less than signs won't show up)