Question

Can someone help figure these out?

Answer 1

@hartnn

Answer 2

ok, so in arithmetic sequences, you know that you need to find the common difference.
whats the common difference for the 1st sequence ?

in geometric sequence, we find the common ratio,
know what that is ?

Answer 3

2.7 to 4.5 is
1.8?

Answer 4

4.5 to 6.3
1.8

Answer 5

yes, so d= common difference = 1.8 for the 1st sequence

Answer 6

a1 = 1st term = 2.7

\(\text{use the general formula now} \\ \large a_n = a_1 +(n-1)d\)

Answer 7

2.7+(n-1)1.8

Answer 8

yeah,
now to get 45th term, just plug in n = 45!

Answer 9

81.9?

Answer 10

And I'm still confused on the error

Answer 11

is something else given ? because even i don't know where to identify the errors ?

Answer 12

Look above the 2 problems
identify the error(s) in planning...

Answer 13

i see the question, but is the 'planning' of solution given ? if nothing is given, just the question, then where to find the error ? :P in the question!? :P

Answer 14

what we can surely do is to find 45th and 6th term

Answer 15

Oh Okay great lol!

Answer 16

and how 81.9 ?

2.7+(45-1)1.8 = .. ?

Answer 17

45-1=44*1.8=79.2+2.7 = 81.9

Answer 18

oh yeah sorry, i took 44 :P
81.9 in correct!

Answer 19

how about the common ratio ?

Answer 20

for 2nd problem

r = common ratio = 2nd term/ 1st term = 3rd term/ 2nd term =....and so on

Answer 21

800/2000=
2/5
320/800
2/5

Answer 22

correct!

r = 2/5
a1 = 1st term = 2000

use the formula for geometric sequence, n'th term
\(\Large a_n = a_1 r^{n-1}\)

Answer 23

and to find 6th term, plug in n= 6 :)

Answer 24

a_n=a_1 r^(n-1)
2000(2/5)^(n-1)
2000(2/5)^(6-1)
2000(2/5)^5
2000(.01024)
20.48

Answer 25

correct! :)

Answer 26

Could you help me with some more?

Answer 27

sure :)

Answer 28

Awesome thank you!