Arithmetic Progression: a=2 d=8 Sn=90 Find n and an ​

Question

Arithmetic Progression:
a=2
d=8
Sn=90
Find n and an ​

in progress 0
Maria 3 weeks 2021-10-08T06:10:35+00:00 2 Answers 0 views 0

Answers ( )

  1. Ava
    0
    2021-10-08T06:11:39+00:00

    Step-by-step explanation:

    answer is 34

    plz mark me as brainlist

  2. Ava
    0
    2021-10-08T06:12:27+00:00

    Answer:

    a=2,d=8,s

    n

    =90

    s

    n

    =

    2

    n

    [2a+(n−1)d]

    90=

    2

    n

    [4+(n−1)8]

    180=n[8n−4]

    180=8n

    2

    −4n

    =8n

    2

    −4n−180=0

    =2n

    2

    −n−45=0

    =2n

    2

    −10n+9n−45=0

    =2n(n−5)−9(n−5)

    =(2n−9)(n−5)

    n=5

    a

    n

    =a+(n−1)d

    a

    n

    =2+(5−1)8

    a

    n

    =2+32

    a

    n

    =34

Leave an answer

Browse
Browse

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