Answer:
[tex] {x}^{3} + 2 {x}^{2} - 15x \\ x( {x}^{2} + 2x - 15) \\ x( {x}^{2} + 5x - 3x - 15) \\ x(x(x + 5) - 3(x + 5) \\ x((x + 5)(x - 3)) \\ {x}^{2} -7x + - 12 \\ {x}^{2} - 4x + 3x - 12 \\ x(x - 4) + 3(x - 4) \\ (x - 4)(x + 3) \\ 3 {x}^{2} - 27 \\ 3( {x}^{2} - 9) \\ 3((x + 3)(x - 3)) \\ \\ the \: hcf \: = (x + 3)[/tex]