Week 2 Pre Calc 11

This week I learned about Finite geometric series, I learned how to find t_n and I also learned how to find the sum of t_1 to t_n.

To find t_n you need t_1 and the common ratio.

So say I was trying to find t_(15), so t_1=4 and the common ratio is 3. This is what you would do.

Then to find the sum of all the 15 t’s, you would add t_1 + t_2 + t_3 +…etc. But the easier way to do it would be to do this.

 

My arithmetic sequence

t_1 = 3, t_2 = 10, t_3 = 17, t_4 = 24, t_5 = 31.

So 3, 10, 17, 24, 31…

t_{50}?   S_{50}?

what I would do first is find out what is t_{50}.

t_n=t_1+(n-1)d

t_{50}=3+49(7)

t_{50}=3+343

t_{50}=346

Now I need to find S_50.

S_n=\frac{n}{2}(t_1+t_{50})

S_{50}=\frac{50}{2}(3+346)

S_{50}=25(349)

S_{50}=8725

So t_{50}=346 and S_{50}=8725.

Week 1 Pre Calc 11

This short week we learned about sequences but more importantly we learned how to get whatever number from the sequence.

Basically if t_1 was 5, then t_2 was 10, and t_3 then with what we learned I could find out what was t_{45}.

this is how.

This is what I learned this past week!