Q. The coefficient of $x^{r}$ in the expansion of $(1 - {x)}^{- 2}$ is
A) $r$
B) $r + 1$
C) $r + 3$
D) $r - 1$
Explanation
(b)
Since, $(1 - x)^{- 2} = 1 + 2x + {3x}^{2} +$….$+ (r + 1)x^{r}$
$\therefore$ Coefficient of $x^{r}$ in ${(1 - x)}^{- 2}$is $(r + 1)$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.