Question

Giúp mình câu 29 nhé!

Answer 1

\(f'\left(x\right)=\dfrac{-3}{\left(x-1\right)^2}\) ; \(f''\left(x\right)=\dfrac{6}{\left(x-1\right)^3}\)

\(f'\left(x\right)+f''\left(x\right)=0\Leftrightarrow\dfrac{-3}{\left(x-1\right)^2}+\dfrac{6}{\left(x-1\right)^3}=0\) (\(x\ne1\))

\(\Leftrightarrow-3\left(x-1\right)+6=0\Rightarrow x=3\)