contestada

1
The numbers of dots in the four
triangular arrays form a sequence.
If n is the number of the term,
which rule could have been
used to determine the first four
terms in the sequence?
n + 1
A
с
n2-n
2
2
B
n² tn
2
D
nz?
n - 1
2

1 The numbers of dots in the four triangular arrays form a sequence If n is the number of the term which rule could have been used to determine the first four t class=

Respuesta :

sqdancefan

9514 1404 393

Answer:

  B.  (n²+n)/2

Step-by-step explanation:

You only need to try n=2 in the answer choices to determine which one gives a result of 3.

  A. (2+1)/2 = 3/2 ≠ 3

  B. (2² +2)/2 = 3 . . . . correct choice

  C. (2² -2)/2 = 1 ≠ 3

  D. (2 -1)/2 = 1/2 ≠ 3

_____

Additional comment

The differences of the sequence 1, 3, 6, 10, ... are increasing, not constant. This means the rule will not be linear, but will be 2nd degree. (Second differences are constant.) This eliminates choices A and D immediately.

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