For a finite sequence of nonzero numbers, the number of variations in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative.
We're asked to look at every pair of consecutive numbers. If the product of that pair is negative, this counts as one variation.ProGMAT wrote:For a finite sequence of non-zero numbers, the number of variations in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative. What is the number of variations in sign for the sequence {1, -3, 2, 5, -4, -6} ?
A. 1
B. 2
C. 3
D. 4
E. 5
Let's examine the pairs of consecutive numbers:
1 and -3: product is negative
-3 and 2: product is negative
2 and 5: product is positive
5 and -4: product is negative
-4 and -6: product is positive
Since 3 pairs of consecutive numbers have negative products, the correct answer is C
Cheers,
Brent
