The first derivative is indeed:
To find the minumum/maximum then you have to solve . What do you get? Afterwards make a sign table to determine where the function increases/decreases.
I suggest finding the lowest common denominators of 3 and 5 and change your exponents into that form:
You can then factor out as a common factor
Can you solve now?
To test whether you have a maximum or minimum check the sign of .
- If you have a maximum
- If you have a minimum
- If you have a point of inflection
There're probably different ways to solve the equation, but if you have to solve:
This means there're no solutions, because there's no value wherefore:
or .
So what's your conclusion?
i solved for x and got x = + or - square root of 3/5
(sorry don't know how to put mathematical functions onto the computer)
and then from the derivative i work out whether it's a maximum or a minimum.
thank you for all your help