# Some Special Cases of Binomial Expansion

Let us take the binomial expansion:

**Example 1:**

If the 21

^{st}and 22

^{nd}terms in the expansion of are equal, find the value of

*x*.

**Solution:**

**Example 2:**

If the Coefficients are equal, find

*r*.

**Solution:**

We have to ignore

*r*= (-6), as a term cannot have negative value.

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*r*= 6