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# Maple Help!!! Watch

1. hello, i am syuck with a bit of maple, so if anyone could help that would be ace.

bacially say i define a function f(x)=x^3 +4x^2+5x+2

and the differential f'(x)= 3x^2 +8x+5

using this differential i find the stationary points on the curve, eg -1 and -5/3

and i find the second derivative to find out if these sp are min/max

eg 6x+8

how doi input the values of x into the second derivative

...............eg in normal maths i would just f''(-1)=2.............f''(-5/3)=-2....................

but how do i do the step above in maple, i can do everything else apart from the line dotted

anyway thanks for any help
2. (Original post by The_TSR_Dunce)
hello, i am syuck with a bit of maple, so if anyone could help that would be ace.

bacially say i define a function f(x)=x^3 +4x^2+5x+2

and the differential f'(x)= 3x^2 +8x+5

using this differential i find the stationary points on the curve, eg -1 and -5/3

and i find the second derivative to find out if these sp are min/max

eg 6x+8

how doi input the values of x into the second derivative

...............eg in normal maths i would just f''(-1)=2.............f''(-5/3)=-2....................

but how do i do the step above in maple, i can do everything else apart from the line dotted

anyway thanks for any help
To input a function into Maple, you need to define the function. g:-> or whatever it is, I'm sure you know. Then do g(-1), etc.
3. In your Maple code you should have something like this.

f:=x^3+4*x^2+5*x+2;
f:=x^3+4*x^2+5*x+2
f1:=diff(f,x);
f1:=3*x^2+8*x+5
f2:=diff(f,x\$2);
f2:=6*x+8

then you will have the stationary points as,

x1:=-1;
x2:=5/3
;

to input the values of x into the 2nd derivative do,

subs(x=x1,f2);
2
subs(x=x2,f2);
-2

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Updated: December 2, 2010
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