[tex]12\sqrt{23 x^{13}}+14\sqrt{23 x^{13}}\\\\=(12+14)\left(\sqrt{23 x^{13}}\right)\\\\=26\left(\sqrt{23 x^{13} }\right)\\\\=26\sqrt{23} \sqrt{x^{13}}\\\\=26\cdot 23^{\tfrac 12} \cdot x^{\tfrac {13}2}[/tex]
