Week 10 – Pre Calc 11

This week in Pre Calc 11, we spent most of the week studying and reviewing for the upcoming midterm. I decided to focus my studying on the first unit we learned this year which was Arithmetic and Geometric Sequences and Series. I found that I needed to review the differences between them and also how to calcualte the value of the last number in an Arithmetic Sequence when the number of terms is given, as I have found these things hard to remember.

While studying, I have recalled that the difference between an Arithmetic and a Geometric Sequence is that an Arithmetic Sequence, increases or decreases by a common difference. Where as a Geometric Sequence increases or decreases by a common ratio.

I also reviewed how to find the value of the last number in an Arithmetic Sequence, when the number of terms is given. For example, in the sequence:  7+11+15+19… we need to determine the value for term 12. We already know that 7 is our first term and that this sequence has a common difference of +4, which means that in order to determine tha value of term 12 we will need to input the information that we already know into the equation t_n = t_1 + (n-1)(d), as I have shown in the example below.

After solving the equation, you now know how to calculate any term in the sequence that might be asked. This week I also reviewed the differences of how you can tell if a Geometric Series is diverging or converging. To determine if it is diverging or converging, you look at the value of the common ration of the Geometric Series. If it is diverging, it means that r>1 or that r<-1. If it is converging, it means that 0<r<1 or that -1<r<0. If the Infinite Geometric Series is diverging it means that it will have no sum, however if it is converging than you are able to caculate the sum.

Each of the things that I have mentioned have all been things that I focused my review on over the past two weeks. They were all units that I needed to review as I had forgotten the majority of it.

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