mathematics - Mathematical Rebus

Mathematical Rebus II

Mathematical Rebus III

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$$4\sum_{n=0}^{\infty}\frac{(-1)^n}{2n+1}\\ (-\infty,...,-1,0,1,...,\infty)\times(-\infty,...,-1,0,1,...,\infty)\\ \forall\begin{bmatrix}{-1}&{0}\\ {0}&{-1} \end{bmatrix}$$

Answer

The first line is

equal to Pi.

The second line is

the integers, Z, multiplied by itself, making Z².

The third line is

multiplying some matrix ∀ by the negative identity matrix, negating its value. The letter ∀ negated is A.

All together,

Pi + Z² + A = Pizza.