. Therefore, ABCD is a parallelogram because both pairs of opposite sides are parallel.

lengths of consecutive sides are not equal
slopes of opposite sides are equal
lengths of opposite sides are equal
slopes of consecutive sides are not equal

the third option, lengths of opposite sides are equal.

Step-by-step explanation:

for edg users I just took the test.

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for

if you would like with a question it is easy to get an answer by including some or multi choice options

step-by-step explanation: