Question

The function $f$ defined by $f(x) =x^3 - 3x^2 + 5x + 7$ ,is

• A. increasing in R.
• B. decreasing in R.
• C. decreasing in $(0, \infty)$ and increasing in $(- \infty , 0)$.
• D. increasing in $(0, \infty)$ and decreasing in $(- \infty , 0)$.

Answer 1

Answer: (A)

$f(x)=x^{3}-3 x^{2}+5 x+7$
$f'(x)=3 x^{2}-6 x+5>0$
$f'(x)=3 x^{2}-6 x+5<0$
$x \in \phi$