Question

The function $f(x)=x^2-2x$ is strict decreasing in the interval

• A. $(-\infty ,1)$
• B. $[1,\infty )$
• C. $R$
• D. None of these

Answer 1

Answer: (A)

$f^{\prime }(x)=2x-2=2(x-1)<0$ if $x<1$
i.e. $x\in (-\infty ,1)$. Hence $f$ is strictly decreasing in $(-\infty ,1]$.