The sum of first 6 terms of an arithmetic Sequence is 99 and the 6th team is 39. (a find the sum of x3 and x4 b write the 3rd

Question

The sum of first 6 terms of an arithmetic
Sequence is 99 and the 6th team is 39.
(a find the sum of x3 and x4
b write the 3rd team
@ write the sequence.​

in progress 0
Savannah 1 month 2021-08-16T07:17:16+00:00 1 Answer 0 views 0

Answers ( )

    0
    2021-08-16T07:18:58+00:00

    Step-by-step explanation:

    The sum of the first N terms of the arithmetic sequence

    is

    N*(A1 + An)/2 = SUM

    6*(A1 + A6)/2 = 99

    6*(A1 + 39)/2 = 99

    3(a1+39) = 99

    a1 + 39 = 33

    a1 = -6

    Next for divided difference D, An = a1 + (n-1)*D

    39 = -6 + (6-1)*D

    39 = -6 + 5*D

    45 = 5D

    D = 9

    The sequence is -6, 3, 12, 21, 30, 39

    12+21 = 33

    mark me as brainlist

Leave an answer

Browse
Browse

18:9+8+9*3-7:3-1*13 = ? ( )