another problem with differentiate (1 Viewer)

[wolf7]

find the stationary point on the curve y = (x-1)^3

and also

find the stationary point on the curve y = x^5 and show that it is a point of inflexion

 

[Riviet]

dy/dx=3(x-1)²
3(x-1)²=0
x=1
y=0
.: (1,0) is a stat point

For y=x⁵
y'=5x⁴
y''=20x³
20x³=0
.: x=0
sub x=1 into 2nd deriv:
20(1)³=20
>0
sub x=-1:
20(-1)³=-20
<0
.: (0,0) is a point of infexion

Easy.

 

[wolf7]

sry about that, the second question has nothing to do with the first 1

 

[Riviet]

Yeah i know, two separate functions. n_n

 

[Loz_metalhead]

Yeh im ok at this stuff. I really need to go over it all because I have my first math assessment in 2 weeks. Oh and I think wolf got confused because you substituted the 1 into the derivative. Sub in 0- and 0+...is that right...Lol. I guess its easier to use the 1. Get the same answer anyway. Or am I wrong...hehe