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Examine whether or not there is any term...

Examine whether or not there is any term containing `x^(9)` in the expansion of `(2x^(2) - (1)/(x))^(20)`

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To determine whether there is a term containing \( x^9 \) in the expansion of \( (2x^2 - \frac{1}{x})^{20} \), we will use the Binomial Theorem. ### Step-by-Step Solution: 1. **Identify the General Term**: The general term \( T_{r+1} \) in the expansion of \( (a + b)^n \) is given by: \[ T_{r+1} = \binom{n}{r} a^{n-r} b^r \] Here, \( a = 2x^2 \), \( b = -\frac{1}{x} \), and \( n = 20 \). 2. **Write the General Term**: For our specific case: \[ T_{r+1} = \binom{20}{r} (2x^2)^{20-r} \left(-\frac{1}{x}\right)^r \] Simplifying this, we get: \[ T_{r+1} = \binom{20}{r} (2^{20-r} (x^2)^{20-r}) \left(-1\right)^r \left(\frac{1}{x^r}\right) \] This simplifies to: \[ T_{r+1} = \binom{20}{r} (-1)^r 2^{20-r} x^{2(20-r) - r} \] 3. **Simplify the Exponent of \( x \)**: The exponent of \( x \) in the term is: \[ 2(20 - r) - r = 40 - 2r - r = 40 - 3r \] Therefore, we have: \[ T_{r+1} = \binom{20}{r} (-1)^r 2^{20-r} x^{40 - 3r} \] 4. **Set the Exponent Equal to 9**: We want to find \( r \) such that: \[ 40 - 3r = 9 \] Rearranging gives: \[ 3r = 40 - 9 = 31 \] Thus: \[ r = \frac{31}{3} \] 5. **Check if \( r \) is an Integer**: Since \( r = \frac{31}{3} \) is not an integer, there is no valid \( r \) that satisfies this equation. 6. **Conclusion**: Since there is no integer value of \( r \) that results in a term containing \( x^9 \), we conclude that there is no term containing \( x^9 \) in the expansion of \( (2x^2 - \frac{1}{x})^{20} \). ### Final Answer: No such term exists.
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