Question

help please
find the 9th term of the sequence.
a4=3/4 and a8=1/2 ; a9= ???

Answer 1

Let a be the first term and d be c.d.
tn=a+(n-1)d
3/4=a+(4-1)d=a+3d
1/2=a+(8-1)d=a+7d
subtract to get the value of d and then a9=a8+d

Answer 2

i guess this is an arithmetic sequence?

Answer 3

i did this problem twice already and i got two different answers.
i got 3/4 and the second time i got 1/2

Answer 4

i gave the the solution considering it as an arithmetic sequence.
you can also solve it as any other sequence e.g.,geometric

Answer 5

is it arithmetic sequences you are studying istinkatmath1?

Answer 6

yes @cwrw238

Answer 7

\[4d=\frac{ 1 }{ 2 }-\frac{ 3 }{ 4 }=\frac{ 2-3 }{4 }=-\frac{ 1 }{ 4 },d=-\frac{ 1 }{ 16 }\]
\[a9=\frac{ 1 }{ 2 }+\frac{ -1 }{ 16 }=\frac{ 8-1 }{ 16 }=\frac{ 7 }{ 16 }\]

Answer 8

i got it thanks !(: