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Find the 
13^("th ") term of the geometric sequence 
1,-3,9,dots
Answer:

Find the 13th  13^{\text {th }} term of the geometric sequence 1,3,9, 1,-3,9, \ldots \newlineAnswer:

Full solution

Q. Find the 13th  13^{\text {th }} term of the geometric sequence 1,3,9, 1,-3,9, \ldots \newlineAnswer:
  1. Identify Geometric Sequence: The given sequence is a geometric sequence, which means each term after the first is found by multiplying the previous term by a common ratio rr. To find the 13th13^{\text{th}} term, we need to identify the common ratio and use the formula for the nthn^{\text{th}} term of a geometric sequence, which is an=a1×r(n1)a_n = a_1 \times r^{(n-1)}, where ana_n is the nthn^{\text{th}} term, a1a_1 is the first term, and rr is the common ratio.
  2. Find Common Ratio: We can find the common ratio by dividing the second term by the first term. So, r=31=3r = \frac{-3}{1} = -3.
  3. Calculate 1313th Term: Now that we have the common ratio, we can use the formula to find the 1313th term. Plugging in the values, we get a13=1×(3)131=1×(3)12a_{13} = 1 \times (-3)^{13-1} = 1 \times (-3)^{12}.
  4. Calculate 1313th Term: Now that we have the common ratio, we can use the formula to find the 1313th term. Plugging in the values, we get a13=1×(3)131=1×(3)12a_{13} = 1 \times (-3)^{13-1} = 1 \times (-3)^{12}. Calculating (3)12(-3)^{12}, we get 531441531441, since (3)12(-3)^{12} means multiplying 3-3 by itself 1212 times, and a negative number raised to an even power results in a positive number.
  5. Calculate 1313th Term: Now that we have the common ratio, we can use the formula to find the 1313th term. Plugging in the values, we get a13=1×(3)131=1×(3)12a_{13} = 1 \times (-3)^{13-1} = 1 \times (-3)^{12}. Calculating (3)12(-3)^{12}, we get 531441531441, since (3)12(-3)^{12} means multiplying 3-3 by itself 1212 times, and a negative number raised to an even power results in a positive number. Therefore, the 1313th term of the sequence is a13=1×531441=531441a_{13} = 1 \times 531441 = 531441.