Verified Answer :

  • Apply the Binomial Theorem to identify the expansion formula: \((z+1)^6 = \sum_{k=0}^{6} \binom{6}{k} z^{6-k}\).
  • Use Pascal's Triangle to determine the coefficients for the 6th row: 1, 6, 15, 20, 15, 6, 1.
  • Substitute these coefficients back into the expansion formula.
  • The final expansion is \(\boxed{z^6 + 6z^5 + 15z^4 + 20z^3 + 15z^2 + 6z + 1}\).

Explanation

  1. Understanding the Binomial Theorem

To expand the expression \((z+1)^6\), we use the Binomial Theorem. The theorem states that for any non-negative integer \(n\), the expansion of \((z+w)^n\) is given by:
\[(z+w)^n = \sum_{k=0}^{n} \binom{n}{k} z^{n-k} w^k\]
In our case, \(n=6\), \(z=z\), and \(w=1\). Therefore, the expression becomes:
\[(z+1)^6 = \sum_{k=0}^{6} \binom{6}{k} z^{6-k} 1^k = \sum_{k=0}^{6} \binom{6}{k} z^{6-k}\]

  1. Identifying Coefficients Using Pascal's Triangle

Pascal's triangle is a useful tool to determine the binomial coefficients \(\binom{n}{k}\). Each row \(n\) of the triangle contains the coefficients for the binomial expansion of power \(n\). We generate the rows as follows:

  • Row 0: 1
  • Row 1: 1, 1
  • Row 2: 1, 2, 1
  • Row 3: 1, 3, 3, 1
  • Row 4: 1, 4, 6, 4, 1
  • Row 5: 1, 5, 10, 10, 5, 1
  • Row 6: 1, 6, 15, 20, 15, 6, 1

The coefficients for \(n=6\) are 1, 6, 15, 20, 15, 6, and 1.

  1. Performing the Expansion

Now, we substitute these coefficients into the binomial expansion formula:
\[(z+1)^6 = 1 \cdot z^6 + 6 \cdot z^5 + 15 \cdot z^4 + 20 \cdot z^3 + 15 \cdot z^2 + 6 \cdot z + 1\]
Simplifying this, we get the expanded polynomial:
\[(z+1)^6 = z^6 + 6z^5 + 15z^4 + 20z^3 + 15z^2 + 6z + 1\]
The final expansion is \(\boxed{z^6 + 6z^5 + 15z^4 + 20z^3 + 15z^2 + 6z + 1}\).

Examples

The Binomial Theorem is used in various fields, such as probability, statistics, and computer science. For instance, in probability, if you flip a coin 6 times, the binomial coefficients help you determine the number of ways to get exactly \(k\) heads, which is \(\binom{6}{k}\). Understanding these expansions allows you to quickly calculate outcomes of multiple independent events or model growth and decline patterns in real-world phenomena.