Fix typos in the mathematical companion

Author: eliasnaur

mathematical-companion/main.tex

@@ -77,7 +77,7 @@ \subsection{Polynomial Rings}
 \textbf{degree} of the polynomial. It is an elementary fact that the product
 of polynomials has degree equal to the sum of the degrees of the factors.
 
-We refer to polynomials of degree 0 is \textbf{constant polynomials}. It is
+We refer to polynomials of degree 0 as \textbf{constant polynomials}. It is
 also a fact that a polynomial has a multiplicative inverse, i.e.~it is a
 \textbf{unit}, if and only if it is nonzero constant.
 
@@ -133,7 +133,7 @@ \subsection{Quotient Fields}
 every element of the group except 1 is a generator of the group. Furthermore there
 are no nontrivial proper subgroups. These are elementary facts of group theory.
 
-We refer to this new field as $\fttwo$. It is fact of field theory that all
+We refer to this new field as $\fttwo$. It is a fact of field theory that all
 groups with 32 elements are isomorphic to this one, which justifies the name.
 But bear in mind that, for our purposes, the field was constructed as $\ftwo[x]/
 (x^5 + x^3 + 1)$ and has a distinguished generator $\alpha$ which is a root