1400 SISTEMA DE ECUACIONES 3X3 MÉTODO SUSTITUCIÓN

█(x+y+z=12@4x−y+z=10@3x−2y−3z=−20) Isolate any variable in either equation. Substitute the isolated variable into the other two equations. This creates a new 2x2 system of equations. Solve the 2x2 system using the substitution method. Procedure: Isolate any variable in either equation. Substitute the isolated variable into the other equation. Substitute the resulting value into either equation (eq4 or eq5) to find the value of the other variable. The calculated values ​​of the unknowns are substituted into any of the equations (ec1, ec2, ec3) to find the third unknown.