Question

find the 21st term of this sequence: -4, -1.5, 1, 3.5,....

Answer 1

From the given,
Let a and b be the missing variable of the equation, so:
y=ax+b, from the given
(1) 3a+b=14
(2) 8a+b=-3.5

(2) - (1) should give you 5a=-17.5, so that a=-3.5
Substituting a=-3.5 in (1), 3(-3.5)+b=14 which gives b=24.5

So the equation is y=-3.5x+24.5

Answer 2

may i ask why u turned 3.5 negative? @trumpetmaster7777

Answer 3

looks @trumpetmaster7777 posted reply for a different question in this post hmm

Answer 4

yah cause i dont get it..lol

Answer 5

hmmm

Answer 6

are we humming?

Answer 7

lol ok lets do some math now

Answer 8

you're doing sequence problems, right @ciara_xo

Answer 9

yes sir :p

Answer 10

-4, -1.5, 1, 3.5,....

Answer 11

first term a = ?

Answer 12

-4?

Answer 13

right

Answer 14

common difference d = 3.5-1 = ?

Answer 15

3.4?

Answer 16

how the heck..

Answer 17

3.5 - 1 = 2.5

Answer 18

come back to math ciara

Answer 19

sorry im half asleep rn :/

Answer 20

i can see that :/

Answer 21

i had a rough night too lol but ill snap out of it.

Answer 22

ok, so we have

a = -4
d = 2.5

Answer 23

\(\large a_n = a+(n-1)d\)

Answer 24

you wanto find 21st term, so put n = 21

Answer 25

okay

Answer 26

as you might be familiar with that above, that gives the nth term in arithmetic sequence

Answer 27

\(a_{21} = -4 + (21-1)*2.5\)
= ?

Answer 28

after the parenthesis is that a plus sign?

Answer 29

or multiply?

Answer 30

* = multiply
+ = plus

Answer 31

69=fun time

Answer 32

@trumpetmaster7777 can i help you or your just being immature?

Answer 33

can't help

Answer 34

just a dog

Answer 35

what do you get ciara as final answer

Answer 36

and @ganeshie8 its cause i cant really see it on my computer but im trying to solve it right now

Answer 37

ok its a multiply sign.

Answer 38

ok lemme try it out :)

Answer 39

i got 54..i hope thats right lol

Answer 40

check again

Answer 41

it seems you added 4 to 50, instead of subtracting !

Answer 42

yes thats what i did -.- so its 46?

Answer 43

\(\color{red}{\checkmark}\)

Answer 44

thank you for your help !

Answer 45

np, yw !