Question

Find the value of a for which the function (a+2)x^3-3ax^2+9ax-1 decreases monotonically

Answer 1

\left[a \right] = \left[ \frac{ - \left( -1+9\,ax - 3\,ax^{2}+2\,x^{3}\right) }{x^{3}}\right][a]=[​x​3​​​​−(−1+9ax−3ax​2​​+2x​3​​)​​]