Let f ( x ) = x 9 7 + 9 x 2 7 2 . {\displaystyle \displaystyle f(x)=x^{\frac {9}{7}}+{\frac {9x^{\frac {2}{7}}}{2}}.} (d) Find the x {\displaystyle x} and y {\displaystyle y} coordinates of all the points of inflection.
