We can use distribution property to multiply the polynomial by the monomial.
$$ \begin{aligned} \color{blue}{4x^{26}} \cdot \left( x^{23}-3 \right) &= \color{blue}{4x^{26}} \cdot x^{23} + \color{blue}{4x^{26}} \cdot \left( -3\right) = \\ &= 4x^{49}-12x^{26} \end{aligned} $$