Q. Find the 5th term in the expansion of (x+3y)5 in simplest form.Answer:
Identify General Term: Identify the general term of the binomial expansion.The general term in the expansion of (a+b)n is given by T(k+1)=C(n,k)⋅a(n−k)⋅bk, where C(n,k) is the binomial coefficient "n choose k".
Determine Specific Term: Determine the specific term we are looking for.We want to find the 5th term, which corresponds to k=4 in the general term formula, since the first term corresponds to k=0.
Calculate Binomial Coefficient: Calculate the binomial coefficient for the 5th term.C(5,4)=4!(5−4)!5!=15=5.
Substitute Values: Substitute the values into the general term formula to find the 5th term.T(5)=C(5,4)×x(5−4)×(3y)4=5×x1×(3y)4.
Simplify Term: Simplify the 5th term.T(5)=5×x×(3y)4=5×x×(81y4)=405x×y4.
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