archnisse.blogg.se

Aritmetisk summa:

£ \sum_{n}^{k} \biggl ( x*k \biggl ) = \frac{första termen+sista termen}{2}* antalet termer £

 

Geometrisk summa:

Första termen $ * \frac{kvoten^{antalet termer}-1}{kvoten - 1} $

 

Exempel på geometrisk summa:

£\sum_{n=1}^{10}\frac{2^n}{3^n} = \frac{2}{3}\frac{\frac{2}{3}^{10} - 1}{\frac{2}{3} - 1}£

£ \biggl \{ \frac{\frac{2}{3}}{\frac{-1}{3}} = -2 \biggl \} £

£ -2 * (\frac{2}{3}^{10} - 1) = 2-2(\frac{2}{3})^{10} £

£ \frac{2}{3}^{10} = 0.0173.. £

£2-0.03.. =1.96..£

 

Also, kom ihåg:

 

£ \cos²2x = \frac{\cos x + 1}{2} £

That is some good shit