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Anonymous
June 9, 2022
Solved

mathcad adding two equations with one variable

  • June 9, 2022
  • 2 replies
  • 2662 views

I checked this section for a similar question and could not locate one. It's simple one I'm guessing but I just cant figure it out.

 

Two equations: 3x^2 + 4x -7 and 5x^2-7x+3

 

(or whatever one variable equation).

 

How can I add them in mathcad so I get the answer 8x^2 -3x-4 ?

 

Thanks. Mr Noob....

Best answer by ttokoro

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2 replies

ttokoro
21-Topaz I
ttokoro21-Topaz IAnswer
21-Topaz I
June 9, 2022

image.pngimage.pngimage.png

t.t.
    A
    Anonymous
    June 10, 2022

    Thanks for your Explanation.

    W
    Werner_E25-Diamond I
    25-Diamond I
    June 9, 2022

    What you show are not equations.

    If your goal is just to do calculation using unknown variables not assigned a value, you have to use symbolic evaluation as ttokoro had shown.

    You get the symbolic "equal sign" (the right arrow) either via the keyboard short (Ctrl and .) or via the menu: Math-Operators-Definition and Evaluation.

    L
    LucMeekes23-Emerald IV
    23-Emerald IV
    June 10, 2022

    "What you show are not equations."

    But both Mathcad and Prime are happy to treat such expressions as equations, assuming that their evaluation result equals 0:

    LucMeekes_0-1654863739281.png

    LucMeekes_1-1654863747517.png

    Success!
    Luc

    W
    Werner_E25-Diamond I
    25-Diamond I
    June 10, 2022
    assuming that their evaluation result equals 0:

    An assumption which is mathematically doubtful, but often convenient when working with Mathcad.

     

    Adding two equations would mean to me to add

    2x +3y  =8z

    and

    5x-4y=-3z

    and get as a result

    7x-y=5z

    Thats something neither Mathcad nor Prime can do in a natural way.

    It also would be beneficial to be able to do operations like "add 4y" to both sides of an equation or to be able to have access to the LHS or RHS of an equation, but unfortunately the symbolics is not capable enough to provide the necessary operators, functions and modifiers.

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