Q. If $r$ is a real number such that $|r| < 1$ and if $a = 5(1 - r),$ then
A) $0 < a < 5$
B) $- 5 < a < 5$
C) $0 < a < 10$
D) $0 \leq a < 10$
Explanation
(c)
Since, $|r| < 1\ \ \Rightarrow \ \ - 1 < r < 1$
Also, $a = 5(1 - r)$
$\Rightarrow \ \ 0 < a < 10$ $\left\lbrack \begin{array}{r}
\because\ at\ r = - 1,\ \ \ a = 0 \\
and\ at\ r = 1,\ \ \ \ a = 0
\end{array} \right\rbrack$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.