Question

Find zeroes of cubic polynomial x^3+2x^2-9x-18

Answer 1

$\Large\underline{\sf \green{ Solution:}}$

$\sf\implies{x}^{3} + {2x}^{2} - 9x - 18 \\ \\\sf\implies({x}^{3} + {2x}^{2}) ( - 9x - 18) \\ \\ \sf\implies {x}^{2} (x + 2) - 9(x + 2) \\ \\\sf\implies ( {x}^{2} - 9)(x +2) \\ \\ \sf\implies ( {x}^{2} - {3}^{2} )(x + 2) \\ \\ \large \sf\implies (x + 3)(x - 3)(x + 2)$

$\Large\underline{\sf \green{Identity\:used:}} \\ \\ \large \sf \implies a^2 - b^2 = (a-b)(a+b)$