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Re: Adding equations

• To: mathgroup at smc.vnet.net
• Subject: [mg14385] Re: [mg14342] Adding equations
• From: "Kevin J. McCann" <kevinmccann at Home.com>
• Date: Sun, 18 Oct 1998 15:09:52 -0400
• Sender: owner-wri-mathgroup at wolfram.com

eq1 = a == b
eq2 = c == d

Thread[eq1 + eq2,Equal]

a+c==b+d

The "Equal" in the Thread is the key.

Kevin

-----Original Message-----
From: Lawrence Walker <lwalker701 at earthlink.net> To:
mathgroup at smc.vnet.net
Subject: [mg14385] [mg14342] Adding equations


>Group:
>
>I've been trying to add two equations as follows:
>
>In[4]:=
>    a==b;
>In[5]:=
>    c==d;
>In[6]:=
>    %4+%5
>Out[6]=
>    (a==b)+(c==d)
>
>The result I was looking for is (a+c)==(b+d). The following works but it
>seems clumsy. In[7]:=
>    %4[[1]]+%5[[1]]==%4[[2]]+%5[[2]] Out[7]=
>    a+c==b+d
>Is there a way to elegantly add (sub, mult, div) two equations?  Also is
>there an elegant way to add (sub, mult, div) an expression to both
>sides of an equation?
>
>Lawrence Walker
>
>