Q. If $a,\ b$ and $c$ are distinct positive real numbers in AP, then the roots of the equation $ax^{2} + 2bx + c = 0$ are

A) Imaginary
B) Rational and equal
C) Rational and distinct
D) Irrational
Explanation

(c)
Since, $b = \frac{a + c}{2}$ ...(i)
Now, discriminant, $D = B^{2} - 4AC$
$= 4b^{2} - 4ac$
$= 4\left( \frac{a + c}{2} \right)^{2} - 4ac$ [from Eq. (i)]
$= (a - c)^{2} \geq 0$
$\therefore$ Roots of the given equation are rational and distinct

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.