The general term of $\left(x+\frac{1}{x^{2}}\right)^{6}$ is $T_{r+1}={ }^{6} C_{r} x^{r}\left(\frac{1}{x^{2}}\right)^{6-r}$ $={ }^{6} C_{r} x^{r-12+2 r}$ For independent of $x$, $r-12+2 r=0 $ $\Rightarrow 3 r=12 $ $\Rightarrow r=4$ $\therefore$ Required term $={ }^{6} C_{4}=\frac{6 \times 5}{2 \times 1}=15 $
The binomial theorem formula is used in the expansion of any power of a binomial in the form of a series. The binomial theorem formula is
Properties of Binomial Theorem
The number of coefficients in the binomial expansion of (x + y)n is equal to (n + 1).
There are (n+1) terms in the expansion of (x+y)n.
The first and the last terms are xn and yn respectively.
From the beginning of the expansion, the powers of x, decrease from n up to 0, and the powers of a, increase from 0 up to n.
The binomial coefficients in the expansion are arranged in an array, which is called Pascal's triangle. This pattern developed is summed up by the binomial theorem formula.