# MATLAB: How to simplify a common factor in a symbolic equation

simplifyingsymbolic

My code is as follows
``syms I_1   phi_1_d2   R_1   f_g   mu_1   I_2   phi_2_d2   R_2   mu_2eq_1= mu_1== I_1 * phi_1_d2 + R_1 * f_g;eq_2= mu_2== I_2 * phi_2_d2 - R_2 * f_g;eq_1= expand(eq_1 * (I_2 * R_1));eq_2= expand(eq_2 * (I_1 * R_2));eq_3= eq_1 - eq_2;eq_3= collect(eq_3, [I_1, I_2]);eq_3= collect(eq_3, f_g);eq_4= eq_3 / ((I_2 * (R_1 ^2)) + (I_1 * (R_2 ^2)));eq_4= collect(eq_4, f_g)``
With the output being
``eq_4 = (R_1*mu_1*I_2 + (-R_2*mu_2)*I_1)/(I_2*R_1^2 + I_1*R_2^2) == ((I_2*R_1^2 + I_1*R_2^2)/(I_2*R_1^2 + I_1*R_2^2))*f_g + (I_1*I_2*(R_1*phi_1_d2 - R_2*phi_2_d2))/(I_2*R_1^2 + I_1*R_2^2)``
This is correct as far as I can tell, however I'm unsure how to make matlab recognise that the coefficient for the f_g term is 1
Any help would be appreciated, I am new to MATLAB and unfamiliar with the symbolic toolkit

``simplify(expand(eq_4))ans =I_2*R_1^2 + I_1*R_2^2 ~= 0 & I_2*(R_1*mu_1 + I_1*R_2*phi_2_d2) == I_2*f_g*R_1^2 + I_1*I_2*phi_1_d2*R_1 + I_1*f_g*R_2^2 + I_1*mu_2*R_2``
``combine(eq_4)ans =(I_2*R_1*mu_1 - I_1*R_2*mu_2)/(I_2*R_1^2 + I_1*R_2^2) == f_g + (I_1*I_2*(R_1*phi_1_d2 - R_2*phi_2_d2))/(I_2*R_1^2 + I_1*R_2^2)``