Q. Find the 2nd term in the expansion of (x−8)8 in simplest form.Answer:
Use Binomial Theorem: To find the 2nd term in the expansion of (x−8)8, we will use the binomial theorem. The general form of the k-th term in the expansion of (a+b)n is given by T(k)=C(n,k−1)⋅a(n−k+1)⋅b(k−1), where C(n,k) is the binomial coefficient "n choose k". For the 2nd term, k=2.
Calculate Binomial Coefficient: Calculate the binomial coefficient for the 2nd term, which is C(8,2−1)=C(8,1). The binomial coefficient C(n,k) is calculated as k!⋅(n−k)!n!, where “!“ denotes factorial.
Compute C(8,1): Compute C(8,1) using the formula for binomial coefficients. C(8,1)=1!⋅(8−1)!8!=18=8.
Calculate Powers of a and b: Now, we need to calculate the rest of the 2nd term using the powers of a and b. In our case, a=x and b=−8. For the 2nd term, a(n−k+1)=x(8−2+1)=x7 and b(k−1)=(−8)(2−1)=−8.
Combine to Get 2nd Term: Combine the binomial coefficient with the powers of a and b to get the 2nd term. The 2nd term is 8×x7×(−8)=−64×x7.
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