Riemann's Zeta Function

$\zeta (n)=\sum _{k=1}^{\infty }\frac{1}{k^n}$

Fundamental Theorem of Calculus for Ordinary Integrals

${\int }_{x=a}^y\frac{df(x)}{dx}dx=f(y)-f(a)$

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The Area Under a Curve

${\int }_{x=a}^{x=b}f(x)dx$

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De Moivre's Theorem

$e^{i\theta }=\cos \theta +i\sin \theta$

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Math in Normal Flow

I am a paragraph of text $x+1$ with math inline.

Fractions

$\frac{x+1}{2}$

$x+\frac{x+1}{2}$

$\frac{B}{C}+\frac{B+\frac{D}{E}}{C}+\frac{B+\frac{D+\frac{F}{G}}{E}}{C}+\frac{B}{C+\frac{D}{E+\frac{F}{G}}}$

Operator Stretching

$(x+\frac{x+1}{2})$

$y\left(\prod _x\frac{x+\frac{x+1}{2}}{x+\frac{x+1}{2}}\right)$

$\left[\begin{array}{ccc}{a}_{11}& a_{12}& a_{13}\\ b_{21}& b_{22}& b_{23}\\ c_{31}& c_{32}& c_{33}\end{array}\right]$

Square Roots

$\sqrt{x+1}$

$\sqrt{\frac{x+1}{x+2}}$