Q. Find the 3 rd term in the expansion of (3x−2)4 in simplest form.Answer:
Use Binomial Theorem: To find the 3rd term in the expansion of (3x−2)4, we will use the binomial theorem. The binomial theorem states that the nth term in the expansion of (a+b)m is given by the formula: T(n)=C(m,n−1)⋅a(m−n+1)⋅b(n−1), where C(m,n−1) is the binomial coefficient. For the 3rd term, n=3.
Calculate Binomial Coefficient: First, we calculate the binomial coefficient for the 3rd term, which is C(4,3−1) or C(4,2). The binomial coefficient C(4,2) is calculated as 2!⋅(4−2)!4!, which simplifies to 2⋅14⋅3=6.
Calculate Powers of a and b: Next, we calculate the powers of a and b for the 3rd term. Since a is 3x and b is −2, and we are looking for the 3rd term (n=3), we have a4−3+1=(3x)2 and b0.
Multiply Coefficient and Powers: Now we multiply the binomial coefficient by the powers of a and b. So the 3rd term is 6×(3x)2×(−2)1. This simplifies to 6×9x2×−2, which is −108x2.
Final Result: Therefore, the 3rd term in the expansion of (3x−2)4 in simplest form is −108x2.
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