[tex]ax^2 + x -24 =0\\\\\text{If the roots are}~ \alpha ~ \text{and}~ \beta,\\\\\alpha \beta = -\dfrac{24}a \\\\\implies -2 \dfrac 25 = -\dfrac{24} a\\\\ \implies 2 \dfrac 25 = \dfrac{24} a\\\\\implies \dfrac{12}5 = \dfrac{24}a\\\\\implies 12a = 120\\\\\implies a =\dfrac{120}{12} =10[/tex]