MHB Find a and b from the function

[rsyed5]

If f(x)=x^3+ax^2+bx has stationary points at: x= 2 and x= -4/3, find the value of a and b.

In my homework, can't work out, Thanks in advance

 

[chisigma]

If f(x)=x^3+ax^2+bx has stationary points at: x= 2 and x= -4/3, find the value of a and b.

In my homework, can't work out, Thanks in advance

In the stationary points is...

$\displaystyle f^{\ '} (x) = 3\ x^{2} + 2\ a\ x + b = 0\ (1)$

... and that leads to the linear pair of equations...

$\displaystyle 12 + 4\ a + b = 0$

$\displaystyle \frac{16}{3} - \frac{8}{3}\ a + b = 0\ (2)$

Now You have to solve (2) finding a and b...

Kind regards$\chi$ $\sigma$

 

[MarkFL]

I have moved this thread to our Calculus subforum as this problem requires the use of differentiation. I'm going to hold off from helping at the moment because I see others already reading this thread. :D