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Find a and b from the function

rsyed5

New member
Aug 15, 2013
5
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
Feb 13, 2012
1,704
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

Administrator
Staff member
Feb 24, 2012
13,775
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