# Math formulas

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#1 26 February, 2017 - 12:00
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Joined: 5 months 3 weeks ago

#### Math formulas

Hello,
I am trying to remember these formulas.
Any idea?

26 February, 2017 - 12:44
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Joined: 2 years 4 months ago

Yes. Just remember the following words by converting them to some image or something:

1. exp(x) = Sum of factors in a Geometric series over their corresponding Factorial, or just Σ [(x^y)/ y! ] , for y=0 up to y=n

2. sin(x) = A Geometric series of the Alternate Sum of all the factors with an ODD exponent, over the exponent's corresponding Factorial.

3. cos(x) = A Geometric series of the Alternate Sum of all the factors with an EVEN exponent, over their over the exponent's corresponding Factorial.

4. 1/ (1-x) = A simple Geometric series of the Sum of of factors, with an ascending exponent of all the Natural numbers.
or just Σ (x^y), for y=0 up to y=n

5. (1+x)^a. This is kinda hard to remember for combinatorics or algebra exams. But let's try:

(1+x)^a = The Sum of factors in a Geometric series with each factor having as a coefficient: the diminishing product of the exponent over the exponent's corresponding Factorial.

- Nodas

28 February, 2017 - 01:26
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Joined: 5 months 3 weeks ago

Thank you Nodas!
As for the (1+x)^a one, I found it was Newton Binomial theorem...

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