[tex]\text{Given that,}\\\\ab = 8 ~ \text{and}~ a^2 +b^2 = 35\\\\\text{Now,}\\\\(a-b)^2 = a^2 +b^2 -2ab\\\\\implies (a-b)^2 =35 - 2 (8) \\\\\implies (a-b)^2 = 19\\\\\implies a-b = \pm\sqrt{19}\\\\\text{Case 1:}\\\\(a-b)^3 = (a-b)^2(a-b)\\\\\implies (a-b)^3 = 19 \left(\sqrt{19}\right)\\\\\text{Case 2:}\\\\(a-b)^3 = (a-b)^2(a-b)\\\\\implies (a-b)^3 = -19 \left(\sqrt{19}\right)[/tex]
