How to simplify matrix in terms of an equation

Question

I have an matrix in Maxima, let´s say (for simplification of the problem):

A: matrix([2*(a^2+b^2+c^2)])

But I know that:

a^2+b^2+c^2 = 1

How do I simplify that matrix in Maxima in terms of that equation, in order to obtain A = [2]?

Answer 1

I found the solution:

A: matrix([2*(a^2+b^2+c^2)]); eq: a^2+b^2+c^2 = 1; scsimp(A, eq);

Answer 2

You can use tellrat.

(%i1) A:matrix([2*(a^2+b^2+c^2)])
(%o1)                        [     2    2    2  ]
                             [ 2 (c  + b  + a ) ]
(%i2) a^2+b^2+c^2 = 1
                                2    2    2
(%o2)                          c  + b  + a  = 1
(%i3) solve(%,a^2)
                              2       2     2
(%o3)                       [a  = (- c ) - b  + 1]
(%i4) tellrat(%[1])
                                2    2    2
(%o4)                         [c  + b  + a  - 1]
(%i5) algebraic:true
(%o5)                                true
(%i6) rat(A)
(%o6)/R/                             [ 2 ]
(%i7) untellrat(a)
(%o7)                                 []