Q. Use the Binomial Theorem to complete the expansion of (r+s)2. r□+2rs+s2
Binomial Theorem Explanation: The Binomial Theorem states that (a+b)n=Σk=0n(kn)⋅a(n−k)⋅bk, where Σ denotes the sum over k from 0 to n. For (r+s)2, n=2. We need to find the coefficient when k=1.
Calculate Coefficient: Calculate the coefficient using "2 choose 1" which is rac{2!}{1! * (2-1)!} = 2.
Multiply Coefficient: Multiply this coefficient by r2−1×s1 to get the term with rs.2×r2−1×s1=2×r×s=2rs.
Complete Expansion: Now we have the complete expansion: r2+2rs+s2.