Question

identify the 35th term of an arithmetric sequence where a1= -7 and a18= 95 please ?

Answer 1

i have no idea how to do it, im confused

Answer 2

See , read the question and tell me what is given.

Answer 3

a1 and a18 are given

Answer 4

Yes Apply formula for them and show me

Answer 5

i dont understand what n is

Answer 6

The 1 and 18 are n

Answer 7

Just substitute 18 in place of n in the formula I gave above and tell me what you get

Answer 8

a18 =18 ( r n=1 ?

Answer 9

See @CCarmichael18 , you have substituted 18 in place of a . I am asking you to substituted 18 in place of n

Answer 10

a18= a(r18-1?

Answer 11

Yes What is 18-1 ??

Answer 12

@shivam_bhalla ,brother its an arithmetic sequence not goemetric

Answer 13

17 ?

Answer 14

. *

Answer 15

Extremely sorry Siddharh

Answer 16

@shivam_bhalla have you been showing me the wrong thing ?

Answer 17

@CCarmichael18
Unfortunately yes.

You have to use this formula

\[\huge a_n = a+(n-1)d\]

d-->common difference = a_2 - a_1 = a_3 - a_2

Answer 18

Try again. Put 18 in place of n and tell me what you get

Answer 19

a18 = a+ (18-1) d ?

Answer 20

a18= a(17) d

Answer 21

You forgot the + sign
It should be
a18= a + (17) d

Also value of a18 is given in the question. Substitute that and tell me what you get

Answer 22

95 = a+ (17) d ?

Answer 23

isnt a = -7 ?

Answer 24

Yes @CCarmichael18 , was just about to tell you

Answer 25

Now solve and tell me d = ?

Answer 26

95 = -7+ (17) d ?
d= 6?

Answer 27

Great. Now what we have to find in the question.??

Answer 28

the 35th term

Answer 29

Yes. tell me what you will do now ?

Answer 30

i have no idea

Answer 31

See just substitute n=35 in the formula above .
substitute your d and a too and tell me what you get

Answer 32

Any problem @CCarmichael18 ??

Answer 33

yes i still dont get it im doing something wrong

Answer 34

Ok. Go step by step. Tell me what you get when you put n=35 in the formula above

Answer 35

85= -7 + (35-1) d ?

Answer 36

How did you get 85?? It should be a_35

Answer 37

a18= 95 ?

Answer 38

Our task is to find a35

Answer 39

so 35 = -7 + ( 35-1) d?

Answer 40

Not exactly ,It should be
a35 = -7 + ( 35-1) d

And we also found d. Now substitute d and tell me a35=?

Answer 41

197 ?

Answer 42

Exactly! you found out the answer . Good work :)

Answer 43

thank you

Answer 44

Welcome :)