Вычислите производную: 1) f (t)=2lg (t+1) , t=1 2) f(x)= -ln cosx , x=pi/4

1) [latex] f ^{'}(t) = \frac{2}{(t+1) ln10} [/latex] [latex]f ^{'}(1) = \frac{2}{(1+1) ln10} = \frac{1}{ln10}[/latex] 2) [latex] f^{'}(x) = - \frac{1}{cos x} * (-sin x) = tg x f^{'}( \frac{ \pi }{4} ) = tg \frac{ \pi }{4} = 1[/latex]