Q. If $x^{2} + 2ax + 10 - 3a > 0$ for all $x \in R$, then
A) $- 5 < a < 2$
B) $a < - 5$
C) $a > 5$
D) $2 < a < 5$
Explanation
(a)
If $f(x) > 0$ ,then $D < 0$
$4a^{2} - 4(10 - 3a) < 0$
$\Rightarrow \ \ \ (a + 5)(a - 2) < 0$
$\Rightarrow \ - 5 < a < 2$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.