Q. Find the 6 th term in the expansion of (x−3y)7 in simplest form.Answer:
Identify general term: Identify the general term for 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 6th term, which means k=5 because the first term corresponds to k=0.
Calculate binomial coefficient: Calculate the binomial coefficient for the 6th term.C(7,5)=5!×(7−5)!7!=2×17×6=21.
Substitute values: Substitute the values into the general term formula. T(6)=C(7,5)×x(7−5)×(−3y)5=21×x2×(−3y)5.
Simplify term: Simplify the term. T(6)=21×x2×(−243y5)=−5103x2y5.
More problems from Identify a sequence as explicit or recursive