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use the "subs" command to subsitute equations for a variable

Asked by Philosophaie on 20 Sep 2013

Here is a silly question: is there a way to use the "subs" command to subsitute equations for a variable?

eqn = 2*(2*x-1) + 3*(3*x+2) + 4*(4*x-5)=11
eqn1 = subs(eqn, {2*x-1,3*x+2,4*x-5}, {a,b,c}); ???

The result:

2*a+3*b+4*c=11 ???

3 Comments

Azzi Abdelmalek on 20 Sep 2013

What is the aim of doing this?

Philosophaie on 20 Sep 2013

Simplify the viewing of large equation.

Walter Roberson on 20 Sep 2013

It makes a difference as to whether the expressions appear exactly, or if instead you want an algebraic transformation. For example if the code had 2*x-2 and you substituted 2*x-1 -> a, then would you want the result to be a-1 or would you want the substitution to be skipped ?

Philosophaie

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1 Answer

Answer by Azzi Abdelmalek on 20 Sep 2013
syms x a
y=2*(2*x-1);
subs(y,a)

0 Comments

Azzi Abdelmalek

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