Question

вычислить производную f(x)=x(lgx-1) x0=10 . f(x)=(2x+1)/(3x-5) x0=2

Answer 1

$1)\; \; f(x)=x\, (lgx-1)\\\\f'(x)=lgx-1+x\cdot \frac{1}{x\cdot ln10}=lgx-1+\frac{1}{ln10}-\; \; ,\qquad \Big [\; log_{a}b=\frac{1}{log_{b}a}\; \Big ]\\\\f'(10)=lg10-1+\frac{1}{ln10}=1-1+lge=lge\\\\\\2)\; \; f(x)=\frac{2x+1}{3x-5}\\\\f'(x)=\frac{2\, (3x-5)-3(2x+1)}{(3x-5)^2}=\frac{6x-10-6x-3}{(3x-5)^2}=-\frac{13}{(3x-5)^2}\\\\f'(2)=-\frac{1}{(6-5)^2}=-\frac{1}{1}=-1$