# Find a and b from the function

#### rsyed5

##### New member
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

##### Well-known member
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

$\chi$ $\sigma$