Find the value of x where the curve $y={{x}^{3}}+2{{x}^{2}}-5x-6$cross the x – axis

Solve the equation${{x}^{3}}-5{{x}^{2}}-x+5=0$ 

Divide a^3x – 26a^2x + 156a^x – 216 by a^2x – 24a^x + 108

if (x – 1), (x + 1) and (x – 2) are factors of the polynomial $a{{x}^{3}}+b{{x}^{2}}+cx-1$. Find a b c respectively