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Find the 
13^("th ") term of the geometric sequence 
7,-21,63,dots
Answer:

Find the 13th  13^{\text {th }} term of the geometric sequence 7,21,63, 7,-21,63, \ldots \newlineAnswer:

Full solution

Q. Find the 13th  13^{\text {th }} term of the geometric sequence 7,21,63, 7,-21,63, \ldots \newlineAnswer:
  1. Find Common Ratio: The first term a1a_1 of the geometric sequence is 77. We need to find the common ratio rr by dividing the second term by the first term.\newlineCalculation: r=21/7=3r = -21 / 7 = -3
  2. Calculate 1313th Term: Now that we have the common ratio, we can find the 1313th term (a13a_{13}) using the formula for the nth term of a geometric sequence: an=a1r(n1)a_n = a_1 \cdot r^{(n-1)}.\newlineCalculation: a13=7(3)131=7(3)12a_{13} = 7 \cdot (-3)^{13-1} = 7 \cdot (-3)^{12}
  3. Calculate (3)12(-3)^{12}: We need to calculate (3)12(-3)^{12}. Since 1212 is an even number, the result will be positive.\newlineCalculation: (3)12=531441(-3)^{12} = 531441
  4. Find 1313th Term: Now we can find the 1313th term by multiplying the first term by (3)12(-3)^{12}.\newlineCalculation: a13=7×531441=3720087a_{13} = 7 \times 531441 = 3720087

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