The function $f(x) =\frac{x}{2}+\frac{2}{x},x≠0$ is increasing on (A) (-∞, -2) Choose the correct answer from the options given below: |
(B) only (B) and (D) only (A) and (C) only (C) and (D) only |
(A) and (C) only |
The correct answer is Option (3) → (A) and (C) only $f(x)=\frac{x}{2}+\frac{2}{x},\;x\ne0$ $\frac{df}{dx}=\frac{1}{2}-\frac{2}{x^2}$ Increasing when $\frac{df}{dx}>0$ $\frac{1}{2}-\frac{2}{x^2}>0$ $\frac{1}{2}>\frac{2}{x^2}$ $x^2>4$ $|x|>2$ Hence increasing for $x<-2$ and $x>2$ From the given options this corresponds to (A) $(-\infty,-2)$ and (C) $(2,\infty)$ The function is increasing on $(-\infty,-2)$ and $(2,\infty)$. |