How to linearize this equation by Taylor function?

or otherwise written:

sin(phi2)*sin(psi1(t))*lk*m1*(diff(psi1(t), t, t))+sin(phi2)*(diff(psi1(t), t))^2*cos(psi1(t))*lk*m1

Some one can help me?

Helo,

how can i export big equations to MS WORD? I trying copy by clicking RMB on equation and paste to WORD but i see only "null". What i can doo now?

I have a very large set of equations that calculates for a long time. Up until now, I have designated the second derivatives and copied the finished equation to another program to do the simulation. But with this file I can hardly do anything because the equations are too long. Even saving a file after computation is not easy. Export to PDF takes 20 minutes and the file has 120 MB and 1000 pages. Recording to .mw has not gone yet due to the occurrence of a write error message. I have 16 GB of RAM and after calculation is 14 GB in use.

5._Równanie_z_5_niewiadomymi.mw
Any suggestions?

Hello!
I have a problem with calculations. I have a worksheet and it calculated on some computer but on another i have an error after each equation. I dont have any idea why. When i click on error i see "Sorry, we do not have specific information about your error. " What can i doo with this?

Hello,

I want to determine the unknown out of the equation, and I do not know why I have such an error.                             

Error, (in MTM:-solve) {5*x-3 = 19} is not valid equation or expression

Why function Solve doesn't work?