Помогите,кто может!!!!!!!

№1)  =√75(cos² (7π/12) - sin² (7π/12))=√75*cos2*(7π/12) = √75cos(7π/6) = √75cos(π/6) = -√75 *√3/2=-15/2 = -7,5 №2) D(f) = (-∞;-1)∪(-1;∞)    (х+1≠0, х≠-1)