Question

If $y=f\left(x\right)$ is monotonic decreasing at $x=a$, then

• A. $f^{\prime }\left(a\right)=0$
• B. $f^{\prime }\left(a\right)>0$
• C. $f^{\prime }\left(a\right)<0$
• D. $f^{\prime }\left(a\right)\ge 0$

Answer 1

The correct option is C $f^{\prime }\left(a\right)<0$

If the curve $y=f\left(x\right)$ is monotonically decreasing at a, then the slope of that curve at a, should be lesser than $0.$
Or
$f^{\prime }(x{)}_{x=a}<0$.