=12√2cos225=12√2cos(180+45)=12√2(-cos45)= -12√2 *<span>√2/2= -12</span>
F(x)=ctgx+x
f'(x)=-1/sin² x+1=0
sinx<>0
x<>πk
sin²x-1=0
sin²x=1
sinx=1
x=π/2+2πK
sinx=-1
x=-π/2+2πK
объединяем
x=π/2+πK K-целое
Ecli y=(5/x²) +4x, to x≠0.
Ecli y=5/(x²+4x), to x²+4x≠0,x(x+4)≠0, x≠0 ∧ x≠-4.