Question

Find the 20th term of the arithmetic sequence 7, 3, -1, -5, …

I got -62 but thats not even a choice

Answer 1

hey the first term is 7 and the common differnce is -4...so just apply the formula to get the 20th term...i guess u might have done calculation mistake

Answer 2

what is the formula again?

Answer 3

oh i got it its -69

Answer 4

its -->
a + (n - 1)*d
a = first term
d= common difference
n= no of term u wanna find the value of here n= 20...

Answer 5

@Ratedover u r correct/...

Answer 6

Find S15 for 1 + 1.5 + 2.25 + 3.375 +... I know the formula

Answer 7

S15 does it mean sum of 15 terms???

Answer 8

yes and i got it lol thanks one more question Find the 10th term of the sequence whose nth term is given by the formula tn = (-1)n+1/n. I have no clue

Answer 9

isnt it given wether its ap or gp???

Answer 10

what..

Answer 11

its damn too easy just plug 10 on place of "n"

Answer 12

@Ratedover solved??

Answer 13

oh....
well i feel stupid

Answer 14

@Ratedover u shouldnt feel the same....

Answer 15

Find S25 for 1/2 + 1 + 3/2 + 2 +.. how about this one, osrry I really have a hard time with sequence

Answer 16

its an arithmetic series with a = 1/2 and d = 1/2...so just apply the formula
S25 = (25/2)*[2a + (n - 1)d]

Answer 17

OHHHH ok yeah that helps a lot thank you

Answer 18

anytime!!!!!!