Matematika/Matematinės eilutės: Skirtumas tarp puslapio versijų

Ištrintas turinys Pridėtas turinys
58 eilutė:
:<math>\arctan x =x-\frac{x^3}{3}+\frac{x^5}{5}-\frac{x^7}{7}+\frac{x^9}{9}-\frac{x^{11}}{11}+...+(-1)^{n+1}\frac{x^{2n-1}}{2n-1}+... \quad (|x|<1).</math>
 
 
*Įrodymas, kad
:<math>\frac{1}{1-x}=1+x+x^2+x^3+x^4+x^5+...+x^n+..., \quad kai \;\; |x|<1.</math>
:<math>
\begin{align}
&\text{Let }s = a + ar + ar^2 + ar^3 + \cdots + ar^{n-1}. \\[4pt]
&\text{Then }rs = ar + ar^2 + ar^3 + ar^4 + \cdots + ar^{n} \\[4pt]
&\text{Then }s - rs = s(1-r) = a-ar^{n},\text{ so }s = a \frac{1-r^{n}}{1-r}.
\end{align}
</math>
 
*Į eilutę
eilutė 88 ⟶ 78:
:<math>1+x+x^2+x^3+x^4+x^5+...+x^n=1-0.3+0.3^2-0.3^3+0.3^4-0.3^5+0.3^6-0.3^7+0.3^8-0.3^9+0.3^{10}=0.769232131.</math>
 
 
*Įrodymas, kad
:<math>\frac{1}{1-x}=1+x+x^2+x^3+x^4+x^5+...+x^n+..., \quad kai \;\; |x|<1.</math>
:<math>
\begin{align}
&\text{Let }s = a1 + arr + arr^2 + arr^3 + \cdots + ar^{n-1}. \\[4pt]
&\text{Then }rs = arr + arr^2 + arr^3 + ar^4 + \cdots + ar^{n} . \\[4pt]
&\text{Then }s - rs = 1,\text{ so }s(1 - r) = a-ar^{n}1,\text{ soand thus }s = a \frac{1-r^{n}}{1-r}.
\end{align}
</math>
 
===Paprasti denominatoriai===