grab one side of an equation

Question

Is there a simple way to grab or reference one side of an equation?

Minimal example of what I mean:

    eq = x^2==3x
    (*Pseudo Code*)
    in: Grab_lefthandside(eq)
    out: x^2

@AskingQuestions. Everything (basically) in Mathematica is an expression of which you can take Parts. Sin[x][[1]] givesx, for instance. EvenGraphicsobjects: look atFullForm[Plot[x, {x, 0, 1}]]`. — march, Aug 30 '16 at 16:43

score 4 · Accepted Answer · answered Aug 30 '16 at 14:10

4

You can change Equal to List and you will have the list of left and right hand sides of the equation.

First[List @@ (x^2 == 3 x)]

answered Aug 30 '16 at 14:10

Vahagn Tumanyan

3

Part, First, Last, etc. operate on expressions not just a List. There is no need to convert to a List to use them. Try f[a, b, c] // First – Bob Hanlon Aug 30 '16 at 15:27
That is true. However, I wanted to show how one can extract and manipulate all the objects in an expression. – Vahagn Tumanyan Aug 31 '16 at 05:56

1 Answers1