Question

If $a{x}^{n-1}+b{x}^{n-2}+c{x}^{n-3}$ is a cubic polynomial where $n\in N$, then find the value of $n$

Answer 1

General form of a cubic polynomial is $a{x}^3+b{x}^2+cx+d$

$\Rightarrow a{x}^{n-1}+b{x}^{n-2}+c{x}^{n-3}=a{x}^3+b{x}^2+cx+d$

$\Rightarrow n-1=3$ (on comparing the coefficients)

$\Rightarrow n=3+1=4$

$\therefore n=4$