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Find the term, which is independent of x...

Find the term, which is independent of x in the expansion of
`(x^2 + 1/x)^9`

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To find the term independent of \( x \) in the expansion of \( (x^2 + \frac{1}{x})^9 \), we can follow these steps: ### Step 1: Identify the General Term The general term \( T_{r+1} \) in the binomial expansion of \( (a + b)^n \) is given by: \[ T_{r+1} = \binom{n}{r} a^{n-r} b^r \] In our case, \( a = x^2 \), \( b = \frac{1}{x} \), and \( n = 9 \). Thus, the general term becomes: \[ T_{r+1} = \binom{9}{r} (x^2)^{9-r} \left(\frac{1}{x}\right)^r \] ### Step 2: Simplify the General Term Now, we simplify \( T_{r+1} \): \[ T_{r+1} = \binom{9}{r} (x^2)^{9-r} \cdot \frac{1}{x^r} = \binom{9}{r} x^{2(9-r)} \cdot x^{-r} \] This can be rewritten as: \[ T_{r+1} = \binom{9}{r} x^{18 - 2r - r} = \binom{9}{r} x^{18 - 3r} \] ### Step 3: Set the Exponent of \( x \) to Zero To find the term that is independent of \( x \), we need to set the exponent of \( x \) to zero: \[ 18 - 3r = 0 \] ### Step 4: Solve for \( r \) Solving the equation: \[ 18 = 3r \implies r = \frac{18}{3} = 6 \] ### Step 5: Find the Independent Term Now, we substitute \( r = 6 \) back into the general term to find the specific term: \[ T_{7} = \binom{9}{6} x^{18 - 3 \cdot 6} \] Calculating \( T_{7} \): \[ T_{7} = \binom{9}{6} x^{0} = \binom{9}{6} \] Since \( \binom{9}{6} = \binom{9}{3} \): \[ \binom{9}{3} = \frac{9 \times 8 \times 7}{3 \times 2 \times 1} = \frac{504}{6} = 84 \] ### Final Answer Thus, the term independent of \( x \) in the expansion of \( (x^2 + \frac{1}{x})^9 \) is: \[ \boxed{84} \]
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