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Which recursive sequence would produce the sequence 
3,-10,29,dots ?

a_(1)=3 and 
a_(n)=-a_(n-1)-3

a_(1)=3 and 
a_(n)=-2a_(n-1)-4

a_(1)=3 and 
a_(n)=-4a_(n-1)-2

a_(1)=3 and 
a_(n)=-3a_(n-1)-1

Which recursive sequence would produce the sequence 3,10,29, 3,-10,29, \ldots ?\newlinea1=3 a_{1}=3 and an=an13 a_{n}=-a_{n-1}-3 \newlinea1=3 a_{1}=3 and an=2an14 a_{n}=-2 a_{n-1}-4 \newlinea1=3 a_{1}=3 and an=4an12 a_{n}=-4 a_{n-1}-2 \newlinea1=3 a_{1}=3 and an=3an11 a_{n}=-3 a_{n-1}-1

Full solution

Q. Which recursive sequence would produce the sequence 3,10,29, 3,-10,29, \ldots ?\newlinea1=3 a_{1}=3 and an=an13 a_{n}=-a_{n-1}-3 \newlinea1=3 a_{1}=3 and an=2an14 a_{n}=-2 a_{n-1}-4 \newlinea1=3 a_{1}=3 and an=4an12 a_{n}=-4 a_{n-1}-2 \newlinea1=3 a_{1}=3 and an=3an11 a_{n}=-3 a_{n-1}-1
  1. Test First Formula: Let's test each recursive formula given with the initial value a1=3a_{1}=3 to see which one produces the sequence 3,10,29,3, -10, 29, \ldots .
  2. Test Second Formula: First, we test the recursive formula an=an13a_{n}=-a_{n-1}-3 with a1=3a_{1}=3. Calculate a2a_{2} using the formula: a2=a13=33=6a_{2}=-a_{1}-3 = -3-3 = -6. This does not match the second term of the sequence, which is 10-10.
  3. Test Third Formula: Since a2a_{2} does not match the second term of the sequence, we can eliminate the first recursive formula.\newlineNow, let's test the second recursive formula an=2an14a_{n}=-2a_{n-1}-4 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: a2=2a14=2×34=64=10a_{2}=-2a_{1}-4 = -2\times 3-4 = -6-4 = -10.\newlineThis matches the second term of the sequence.
  4. Test Fourth Formula: Now, calculate a3a_{3} using the second recursive formula: a3=2a24=2(10)4=204=16a_{3}=-2a_{2}-4 = -2*(-10)-4 = 20-4 = 16. This does not match the third term of the sequence, which is 2929.
  5. Conclusion: Since a3a_{3} does not match the third term of the sequence, we can eliminate the second recursive formula.\newlineNow, let's test the third recursive formula an=4an12a_{n}=-4a_{n-1}-2 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: a2=4a12=4×32=122=14a_{2}=-4a_{1}-2 = -4\times3-2 = -12-2 = -14.\newlineThis does not match the second term of the sequence, which is 10-10.
  6. Conclusion: Since a3a_{3} does not match the third term of the sequence, we can eliminate the second recursive formula.\newlineNow, let's test the third recursive formula an=4an12a_{n}=-4a_{n-1}-2 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: a2=4a12=4×32=122=14a_{2}=-4a_{1}-2 = -4\times3-2 = -12-2 = -14.\newlineThis does not match the second term of the sequence, which is 10-10.Since a2a_{2} does not match the second term of the sequence, we can eliminate the third recursive formula.\newlineNow, let's test the fourth recursive formula an=3an11a_{n}=-3a_{n-1}-1 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: an=4an12a_{n}=-4a_{n-1}-200.\newlineThis matches the second term of the sequence.
  7. Conclusion: Since a3a_{3} does not match the third term of the sequence, we can eliminate the second recursive formula.\newlineNow, let's test the third recursive formula an=4an12a_{n}=-4a_{n-1}-2 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: a2=4a12=4×32=122=14a_{2}=-4a_{1}-2 = -4\times3-2 = -12-2 = -14.\newlineThis does not match the second term of the sequence, which is 10-10.Since a2a_{2} does not match the second term of the sequence, we can eliminate the third recursive formula.\newlineNow, let's test the fourth recursive formula an=3an11a_{n}=-3a_{n-1}-1 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: an=4an12a_{n}=-4a_{n-1}-200.\newlineThis matches the second term of the sequence.Now, calculate a3a_{3} using the fourth recursive formula: an=4an12a_{n}=-4a_{n-1}-222.\newlineThis matches the third term of the sequence.
  8. Conclusion: Since a3a_{3} does not match the third term of the sequence, we can eliminate the second recursive formula.\newlineNow, let's test the third recursive formula an=4an12a_{n}=-4a_{n-1}-2 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: a2=4a12=4×32=122=14a_{2}=-4a_{1}-2 = -4\times3-2 = -12-2 = -14.\newlineThis does not match the second term of the sequence, which is 10-10.Since a2a_{2} does not match the second term of the sequence, we can eliminate the third recursive formula.\newlineNow, let's test the fourth recursive formula an=3an11a_{n}=-3a_{n-1}-1 with a1=3a_{1}=3.\newlineCalculate a2a_{2} using the formula: an=4an12a_{n}=-4a_{n-1}-200.\newlineThis matches the second term of the sequence.Now, calculate a3a_{3} using the fourth recursive formula: an=4an12a_{n}=-4a_{n-1}-222.\newlineThis matches the third term of the sequence.Since the fourth recursive formula an=3an11a_{n}=-3a_{n-1}-1 with a1=3a_{1}=3 produces the correct second and third terms of the sequence, we can conclude that this is the correct recursive formula for the given sequence.

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