Question

find the common difference, d, for the arithmetic sequence in which a sub1=9 and a sub 20=-29

Answer 1

@Calcmathlete

Answer 2

@Calcmathlete

Answer 3

@Calcmathlete

Answer 4

Use the formula:
\[a_n = a_1 + (n - 1)d\]

Answer 5

how?

Answer 6

can you plz show what to substitute

Answer 7

\[a_n = a_1 + (n - 1)d\]\[a_{20} = a_1 + (20 - 1)d\]\[-29 = 9 + 19d\]Solve for d.

Answer 8

-2

Answer 9

Yup. d = -2

Answer 10

one more

Answer 11

you plz help me with one more?

Answer 12

Alright

Answer 13

In geometric sequence \[a _{3}=2\] and \[r=1/2\] find \[a _{8}\]

Answer 14

Do you know how to do this one?

Answer 15

nope not a bit

Answer 16

Use the formula \[a_n = a_1r^{n - 1}\]

Answer 17

whta do i substitue for a1

Answer 18

First solve for \(a_1\).
\[a_3 = a_1(\frac12)^2\]\[2 = a_1(\frac12)^2\]Can you solve?

Answer 19

a1= 8?

Answer 20

Yup...

Answer 21

y? 1/2 ^2

Answer 22

That's the formula...
\[a_n = a_1r^{n - 1}\]\[a_3 = a_1(r)^{3 - 1}\]\[2 = a_1(\frac12)^2\]

Answer 23

h ok

Answer 24

alright I cant take it from here thx calc

Answer 25

Alright :)

Answer 26

may I have a a medal if its alright with you :)

Answer 27

thx :D

Answer 28

Wait, depends on what your answer is XD

Answer 29

I'll you tom. right now I gt study

Answer 30

lol k :)