Question

What are the first 4 terms of the arithmetic sequence in the graph?

Answer 1

Start from bottom to top. They are asking for the y-intercept of each dot. The following order is the answer: -3, 1, 5, 9.

Answer 2

Answer: In an arithmetic sequence, whose first term is a and difference between a term and its preceding term is d,

the nth term is a+(nâ’1)d and sum of first n terms is n2(2a+(nâ’1)d)

Hence 6th term will be a+5d=8 and 10th term will be a+9d=13

Subtracting first from second, 4d=5 or d=1.25 and a=8â’5â‹…1.25=8â’6.25=1.75

Hence sum of first four terms is 42â‹…(2â‹…1.75+3â‹…1.25)=2â‹…(3.5+3.75)=2â‹…7.25=14.50