Alrighty so this week we started chapter 13 which is our last chapter to cover before reading Flatland. It is a pretty simple chapter and should be easy to pass the test because its just sequences and series of numbers. Basically, just remember the formulas.
There are 2 main types of sequences:
1.) Arithmetic- tn*t1+(n-1)d
n=term # t1=first term d=what you add
2.) Geometric- tn=t1*r^(n-1)
r= what you multiply by
Example: find the formula for the nth term of the arithmetic sequence
3,5,7
tn= 3+(n-1)(2)
tn=3+2n-2
tn=1+2n
Example: find the formula for the nth term of the sequence
3, 4.5, 6.75
divide the second term by the first to get your r.
4.5/3= 3/2 r= 3/2
tn=3(3/2)^n-1
I could use some help on the problems that ask you specifically to find the 200th term for example. I could also use some help with the recursive definitions. THANKSS!!!
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If a problem ask you for the 200th term then all you do is after you write down the equation you plug in the 200 where the n is and that's how you get your answer.
ReplyDeleteAlrighty im going to answer my own question because i understand how to do it now.
ReplyDeleteExample:
if t1=1 and t2=4 find 200th term
tn=1+(n-1)(3)
tn=1+3n-3
tn=-2+3n
Also another thing i was having trouble with is finding multiples of a number between two certain numbers
Example: what are the multiples of 3 between 1 & 100
3,6,9,....99 arithmetic
tn=t1+(n-1)d
99=3+(n-1)(3)
99=3+3n-3
3n=99
n=33