integrate (e^t + e^-t)²

(e^t + e^-t)²

= e^2t + 2 + e^-2t

integral (e^t + e^-t)² dx
= integral e^2t + 2 + e^-2t dx
= (1/2) e^2t + 2t - (1/2)e^-2t + c