There's a minimum turning at . If you want to use the cubic formula to solve for x (at least it's a depressed cubic so that's a start) be my guest. There's no simple way of getting the exact value of x.
Does the book have an answer at the back?
If you want an exact value for the x-coordinate of the minimum turning point, solve the cubic equation by following the process given here: Cubic Formula -- from Wolfram MathWorld
Good luck substituting this exact value into y = f(x) to get the y-coordinate.
Thanks a lot for giving for time...
actually I am studying part time through distant learning and there is no instructor to guide so i thought anyone here can help. hence i posted two questions which only i was not able to solve in last 4 question papers. one is this question and another is
PS: I also tried formula given here http://en.wikipedia.org/wiki/Cubic_equation