Q. Find the 13th term of the geometric sequence 7,−21,63,…Answer:
Find Common Ratio: The first term a1 of the geometric sequence is 7. We need to find the common ratio r by dividing the second term by the first term.Calculation: r=−21/7=−3
Calculate 13th Term: Now that we have the common ratio, we can find the 13th term (a13) using the formula for the nth term of a geometric sequence: an=a1⋅r(n−1).Calculation: a13=7⋅(−3)13−1=7⋅(−3)12
Calculate (−3)12: We need to calculate (−3)12. Since 12 is an even number, the result will be positive.Calculation: (−3)12=531441
Find 13th Term: Now we can find the 13th term by multiplying the first term by (−3)12.Calculation: a13=7×531441=3720087