geometrical applications of calculus (1 Viewer)

[blacktown_]

evaluate a and b if y=x^3-ax^2+bx-3 has stationary points at x=-1 and x=2

please help!!!!!

thankyou

 

[Carrotsticks]

 

[superSAIyan2]

Differentiate with respect to x
dy/dx = 3x^2 - 2ax + b
since x=-1 and 2 are stat pts y'=0
0 = 3 + 2a + b (1)
0 = 12 - 4a + b (2)

Then just solve simultaneously.
(1) - (2) 6a = 9 a = 3/2
when a =3/2 b = -6 (dunno if this is right, did it in my head )

 

[Capt Rifle]

damn beat me to it haha

 

[blacktown_]

Thankyou everyone that answered

 

[Currybear]

How did you get your text like that, im kind of new..

 

[Carrotsticks]

How did you get your text like that, im kind of new..

It's called LaTeX and takes a bit of time to learn to use properly.

http://community.boredofstudies.org/showthread.php?t=234262

 

[lizzy95]

thank you this helped so much!