Which recursive sequence would produce the sequence 2,3,6,… ?a1=2 and an=3an−1−3a1=2 and an=−5an−1+4a1=2 and an=−3an−1+3a1=2 and an=4an−1−5
Q. Which recursive sequence would produce the sequence 2,3,6,… ?a1=2 and an=3an−1−3a1=2 and an=−5an−1+4a1=2 and an=−3an−1+3a1=2 and an=4an−1−5
Test Formula 1: Let's test each recursive formula by applying it to the given initial value and checking if it produces the sequence 2,3,6,….We start with the first option:a1=2 and an=3an−1−3We know a1=2, so let's find a2:a2=3a1−3a2=3×2−3a2=6−3a2=3Now let's find a3:a1=20a1=21a1=22a1=23So far, the sequence matches: a1=24. Let's check one more term to be sure.a1=25a1=26a1=27a1=28The sequence we have from this formula is a1=29, which does not match the expected sequence of an=3an−1−30 because the next term should be a multiple of the previous term, not an=3an−1−31.
Test Formula 2: Let's test the second option:a1=2 and an=−5an−1+4We know a1=2, so let's find a2:a2=−5a1+4a2=−5×2+4a2=−10+4a2=−6This does not match the second term of the sequence, which is 3, so this option is incorrect.
Test Formula 3: Let's test the third option:a1=2 and an=−3an−1+3We know a1=2, so let's find a2:a2=−3a1+3a2=−3×2+3a2=−6+3a2=−3This does not match the second term of the sequence, which is 3, so this option is incorrect.
Test Formula 4: Finally, let's test the fourth option:a1=2 and an=4an−1−5We know a1=2, so let's find a2:a2=4a1−5a2=4×2−5a2=8−5a2=3Now let's find a3:a3=4a2−5an=4an−1−50an=4an−1−51an=4an−1−52This does not match the third term of the sequence, which is an=4an−1−53, so this option is incorrect.
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