Q. d(n)=−5(21)n−1What is the 3rd term in the sequence?
Understanding the sequence formula: Understand the given sequence formula.The sequence is defined by the formula d(n)=−5(21)n−1, which suggests that it is a geometric sequence with a common ratio of 21 and a starting term multiplied by −5.
Finding the 3rd term: Plug in the value of n to find the 3rd term.To find the 3rd term, we substitute n=3 into the formula.d(3)=−5(21)3−1
Calculating the exponent: Calculate the exponent part of the formula. (21)(3−1)=(21)2
Simplifying the exponent: Simplify the exponent.(21)2=41
Multiplying by −5 to get the 3rd term: Multiply the result of the exponent by −5 to get the 3rd term.d(3)=−5×(41)
Performing the multiplication: Perform the multiplication to find the 3rd term.d(3)=−45