Symbolic Math toolbox does not solve equation

Hello everyone, I am attempting to solve an equation via the Symbolic Math toolbox:

syms a b c d e

solve([a^2 + b*c == d^2, b*c==e*a^2],e)

ans =

Empty sym: 0-by-1

However, I seem to be unable to move the solver to produce the correct soluation (d^2-a^2)/a^2.

What am I doing wrong here, and how should I formulate this problem for the solver to work?

Thank you for every hint on this!

Answer 1

[Harald]

Hi,

since you supply two equations, you would also need to solve for two variables.

To let MATLAB do what you did, you could use:

syms a b c d e
s1 = solve(b*c==e*a^2,e);
s2 = solve(a^2 + b*c == d^2, b);
s = simplify(subs(s1, b, s2))

s = 

or

syms a bc d e
s1 = solve(bc==e*a^2,e);
s2 = solve(a^2 + bc == d^2, bc);
s = subs(s1, bc, s2)

s = 

Best wishes,

Harald

[BW]

Thank you for your help Harald, totally makes sense^^