Mathematics for IGCSE & O level - Equations (Section 6 - No. 36)
Which method would be used if asked to 'Solve the following system of equations: y = 2x + 1 and x + y = 5'?
Factorization
Quadratic Formula
Substitution
Completing the Square
Paliwanag
Substitution is generally the easiest method when one equation already expresses a variable in terms of the other.