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Find the number of terms in the expansio...

Find the number of terms in the expansion of
`(2x+3y+z)^(7)`

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To find the number of terms in the expansion of \((2x + 3y + z)^7\), we can use the formula for the number of distinct terms in the expansion of \((x_1 + x_2 + \ldots + x_r)^n\), which is given by: \[ \text{Number of terms} = \binom{n + r - 1}{r - 1} \] where \(n\) is the exponent and \(r\) is the number of different variables. ### Step-by-step Solution: 1. **Identify the values of \(n\) and \(r\)**: - In the expression \((2x + 3y + z)^7\): - The exponent \(n = 7\). - The number of different variables \(r\) (which are \(2x\), \(3y\), and \(z\)) is \(3\). 2. **Apply the formula**: - Substitute \(n\) and \(r\) into the formula: \[ \text{Number of terms} = \binom{n + r - 1}{r - 1} = \binom{7 + 3 - 1}{3 - 1} \] 3. **Simplify the expression**: - Calculate \(n + r - 1\) and \(r - 1\): \[ n + r - 1 = 7 + 3 - 1 = 9 \] \[ r - 1 = 3 - 1 = 2 \] - Thus, we have: \[ \text{Number of terms} = \binom{9}{2} \] 4. **Calculate \(\binom{9}{2}\)**: - The binomial coefficient \(\binom{9}{2}\) is calculated as follows: \[ \binom{9}{2} = \frac{9!}{2!(9-2)!} = \frac{9 \times 8}{2 \times 1} = \frac{72}{2} = 36 \] 5. **Conclusion**: - Therefore, the number of terms in the expansion of \((2x + 3y + z)^7\) is \(36\). ### Final Answer: The number of terms in the expansion of \((2x + 3y + z)^7\) is **36**.
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