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The coefficient of the term involving x^...

The coefficient of the term involving `x^2` in the expansion of `(3x - 1/x)^6` is 1210

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To determine whether the coefficient of the term involving \(x^2\) in the expansion of \((3x - \frac{1}{x})^6\) is 1210, we will follow these steps: ### Step 1: Write the General Term The general term \(T_r\) in the binomial expansion of \((a + b)^n\) is given by: \[ T_r = \binom{n}{r} a^{n-r} b^r \] For our expression \((3x - \frac{1}{x})^6\), we have: - \(a = 3x\) - \(b = -\frac{1}{x}\) - \(n = 6\) Thus, the general term becomes: \[ T_r = \binom{6}{r} (3x)^{6-r} \left(-\frac{1}{x}\right)^r \] ### Step 2: Simplify the General Term Now, we can simplify \(T_r\): \[ T_r = \binom{6}{r} (3^{6-r} x^{6-r}) \left(-1^r \frac{1}{x^r}\right) = \binom{6}{r} 3^{6-r} (-1)^r x^{6-r - r} \] This simplifies to: \[ T_r = \binom{6}{r} 3^{6-r} (-1)^r x^{6-2r} \] ### Step 3: Find the Value of \(r\) for \(x^2\) We want the term where the power of \(x\) is 2: \[ 6 - 2r = 2 \] Solving for \(r\): \[ 6 - 2 = 2r \\ 4 = 2r \\ r = 2 \] ### Step 4: Calculate the Coefficient for \(r = 2\) Now we substitute \(r = 2\) into the general term: \[ T_2 = \binom{6}{2} 3^{6-2} (-1)^2 x^{6-2 \cdot 2} \] Calculating each part: - \(\binom{6}{2} = \frac{6 \times 5}{2 \times 1} = 15\) - \(3^{6-2} = 3^4 = 81\) - \((-1)^2 = 1\) Thus, the coefficient becomes: \[ \text{Coefficient} = 15 \cdot 81 = 1215 \] ### Conclusion The coefficient of the term involving \(x^2\) in the expansion of \((3x - \frac{1}{x})^6\) is 1215, not 1210. Therefore, the statement is false. ---
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