Polynomial ring/Field/Zeroes/Number/Fact

Let ${\displaystyle {}K}$ be a field and let ${\displaystyle {}K[X]}$ be the polynomial ring over ${\displaystyle {}K}$. Let ${\displaystyle {}P\in K[X]}$ be a polynomial (${\displaystyle {}\neq 0}$) of degree ${\displaystyle {}d}$.

Then ${\displaystyle {}P}$ has at most ${\displaystyle {}d}$ zeroes.