Which recursive sequence would produce the sequence 1,−5,13,… ?a1=1 and an=−an−1−4a1=1 and an=−2an−1−3a1=1 and an=−4an−1−1a1=1 and an=−3an−1−2
Q. Which recursive sequence would produce the sequence 1,−5,13,… ?a1=1 and an=−an−1−4a1=1 and an=−2an−1−3a1=1 and an=−4an−1−1a1=1 and an=−3an−1−2
Test Option 1: Let's test the first option: a1=1 and an=−an−1−4. We start with a1=1. To find a2, we use the recursive formula: a2=−a1−4=−1−4=−5. Now, let's find a3: a3=−a2−4=−(−5)−4=5−4=1. This does not match the given sequence since the third term should be 13, not 1.
Test Option 2: Let's test the second option: a1=1 and an=−2an−1−3. We start with a1=1. To find a2, we use the recursive formula: a2=−2a1−3=−2×1−3=−2−3=−5. Now, let's find a3: a3=−2a2−3=−2×(−5)−3=10−3=7. This does not match the given sequence since the third term should be 13, not 7.
Test Option 3: Let's test the third option: a1=1 and an=−4an−1−1. We start with a1=1. To find a2, we use the recursive formula: a2=−4a1−1=−4×1−1=−4−1=−5. Now, let's find a3: a3=−4a2−1=−4×(−5)−1=20−1=19. This does not match the given sequence since the third term should be 13, not 19.
Test Option 4: Let's test the fourth option: a1=1 and an=−3an−1−2. We start with a1=1. To find a2, we use the recursive formula: a2=−3a1−2=−3×1−2=−3−2=−5. Now, let's find a3: a3=−3a2−2=−3×(−5)−2=15−2=13. This matches the given sequence since the third term is indeed 13.
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