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Find the 3 rd term in the expansion of 
(3x+y)^(6) in simplest form.
Answer:

Find the 33 rd term in the expansion of (3x+y)6 (3 x+y)^{6} in simplest form.\newlineAnswer:

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Q. Find the 33 rd term in the expansion of (3x+y)6 (3 x+y)^{6} in simplest form.\newlineAnswer:
  1. Identify Binomial Expansion Form: Identify the general form of the binomial expansion.\newlineThe binomial theorem states that the expansion of (a+b)n(a+b)^n will have terms of the form C(n,k)a(nk)bkC(n, k) \cdot a^{(n-k)} \cdot b^k, where C(n,k)C(n, k) is the binomial coefficient, which can be calculated using the formula C(n,k)=n!k!(nk)!C(n, k) = \frac{n!}{k! \cdot (n-k)!}.
  2. Determine Specific Term: Determine the specific term we are looking for.\newlineWe are looking for the 3rd3^{\text{rd}} term in the expansion, which corresponds to k=2k=2, since the first term corresponds to k=0k=0.
  3. Calculate Binomial Coefficient: Calculate the binomial coefficient for the 33rd term.\newlineUsing the formula for the binomial coefficient, we have C(6,2)=6!2!(62)!=(654321)(214321)=(65)(21)=15C(6, 2) = \frac{6!}{2! * (6-2)!} = \frac{(6 * 5 * 4 * 3 * 2 * 1)}{(2 * 1 * 4 * 3 * 2 * 1)} = \frac{(6 * 5)}{(2 * 1)} = 15.
  4. Write Out 33rd Term: Write out the 33rd term using the binomial coefficient and the variables.\newlineThe 33rd term is given by C(6,2)(3x)62y2=15(3x)4y2C(6, 2) \cdot (3x)^{6-2} \cdot y^2 = 15 \cdot (3x)^4 \cdot y^2.
  5. Simplify 33rd Term: Simplify the 33rd term.\newlineSimplify (3x)4(3x)^4 to get 34×x4=81×x43^4 \times x^4 = 81 \times x^4.\newlineThen, the 33rd term is 15×81×x4×y2=1215×x4×y215 \times 81 \times x^4 \times y^2 = 1215 \times x^4 \times y^2.

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