Hello,

I have the function f(x)= x(8-5x)(28+5x)/2(2+x)^2

Interval(0<x<1.6)

which I have fond the deriviative as

f'(x) = 1/2x(8-5x)(28+5x)/(2+x)^2

I found this using simplyfy as when i try to solve symbolically it say no solution.

Form this I have to solve the equation f'(x)=0 for x to find the maximum of f(x).

However when I put this into solve back all I come up with is 'Illegal function value '

Can you show me how to type it in to solve back please. I had a guess at the maximum value being about 0.8 ish.

Thank you

I HAVE to use teh solve back facility can't do it any other way because that is what is asked of me in the question.