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Week 3 – PreCalc 11

This week we started our new unit on absolute values and radicals. It was a very short week and most of it was review from grade 10 math, except for the new term of what an absolute value is.  Something I found hard to do at first was turning entire radicals into a mixed radical.

example \sqrt{72}

first we need to find two numbers that multiply to 72, with one of them being a perfect square.

\sqrt{8} x \sqrt{9} = \sqrt{72}

because 9 is a perfect square of 3 we can take that and put it as a coefficient leaving only the 8 under the root symbol.

3 \sqrt{8}

this is our final answer.



Week 2 – PreCalc 11

This week in pre-calc 11 we learned about geometric sequences and series. An important part in these is the common ratio, it shows the difference between the terms by the term being multiplied by the constant.

The formula to find the CR is: r= \frac {t_n}{t_n-1}

Example: 4, 8, 16, 32

If you’re looking for the common ratio we need to divide 8 by 4.

r= \frac {8}{4} = 2

You could also do r= \frac {32}{16} = 2 As long as you use a term that precedes t_n as the denominator you will get the right answer for the common ratio.

Week 1 – Precalc 11

In the first week of Pre-Calc we learned how to find the sum of an arithmetic series. An arithmetic series is the sum of all the terms in an arithmetic sequence added together. We used the formula S_n = \frac {n} {2} (t_1 + t_n) to find the sum.

In this formula represents the amount of terms in the sequence. We replace t_1 with the first term in the sequence and t_n with the last term. Once you’ve filled in the variables in the fomula you divide by 2. Then add the first and last terms together.

Ex. 2, 5, 8, 11, 14….59   t_1=2  t_{20}=59

with this information we can solve for S_n

S_{20} = \frac {20} {2} (2+59)

S_{20}= 10(61)




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