1 Topic by m255173 (edited by m255173 2012-10-20 22:53:02)

Topic: graph an Implicit Eq. and its derivative ?

Love this prog.!

Need to find the slope m,
of the tangent line
to the "implicit function":
     y^2= x^3 * (2-x)
@ point: x=1, y= -1

So...I need to find the derivative of y in GRAPH,
and show both curves: y and y' ...

Q1)
- How do I specify and graph,
the above "implicit function",
and * also *
graph the Tangent line to it,
@ x=1, y= -1 ?

Q2)
- I tried this in GRAPH:
     y = (  x^3 * (2-x)  ) ^ (1/2)
but only get the top part.

Wolfram Alpha seems to give both,
top & bottom of the same chart...
    pls see WA:   goo.gl/UuqYX 

Tak for your help, Ivan!
SF99

Re: graph an Implicit Eq. and its derivative ?

You can use Function|Insert relation to insert y^2= x^3 * (2-x) directly. However Graph cannot add tangents to implicit functions, so instead you have to split the function into two functions: f(x)=sqrt(x^3 * (2-x)) and f(x)=-sqrt(x^3 * (2-x)).  These can be inserted in Function|Insert function, and you can add a tangent to them afterwards.

3 Reply by m255173 (edited by m255173 2012-10-20 22:53:21)

Re: graph an Implicit Eq. and its derivative ?

Perfect! 
(learning something new about GRAPH,
every day).

Tusend tak, Ivan...

SF99