Q. If $ab = 4\left( a,b \in R^{+} \right),\$then
A) $a + b \leq 4$
B) $a + b = 4$
C) $a + b \geq 4$
D) None of these
Explanation
(c)
Since,
$AM \geq GM$
$\Rightarrow \frac{a + b}{2} \geq \sqrt{ab}$
$\Rightarrow \frac{a + b}{2} \geq \sqrt{4}\ \ \ (\because ab = 4,$ given)
$\Rightarrow a + b \geq 4$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.