Question

Find the 3rd term of an arithmetic sequence with t2=9/2 and t5=6

A.) 3
B.) 5
C.) 2
D.) 4

I chose 3 and I got it wrong but I can't find where I made my mistake.

Answer 1

If you could type it using the equation box it would be helpful.. I can't tell which ones are subscripts and which ones are actually part of the equation.

Answer 2

Okie :) \[t _{2}=9/2\]

Answer 3

and \[t _{5}=6\]

Answer 4

I redid the problem is it 5?

Answer 5

I'm working on it.

Answer 6

okay :)

Answer 7

I think it would be 5 too, 9/2= 4.5 if you add .75 to it then t3= 5.25 and if you add .75 again then it would equal 6. I'm not quite sure if it's the problem but 5.25 is close to 5.

Answer 8

okay thanks!

Answer 9

\[t_n=t_x+(n-x)*r\]\[t_5=t_2+(5-2)*r\]\[t_5-t_2=3r\]\[r=\frac{3}{2}\]\[t_n=t_2+(n-2)*\frac{3}{2}\]\[t_3=\frac{9}{2}+(3-2)*\frac{3}{2}\]\[t_3=\frac{9}{2}+\frac{3}{2}\]\[\boxed{t_3=6}\]

Answer 10

Hold on, I made an mistake

Answer 11

\[r=0.5\]\[t_n=t_2+(n-2)*0.5\]\[t_3=t_2+(3-2)*0.5\]\[t_3=\frac{9}{2}+0.5\]\[\boxed{\boxed{t_3=5}}\]