Solution methods for equations (linear, quadratic, cubic, simultaneous): (1) Linear ax + b = 0 → x = -b/a (one solution); (2) Quadratic: factorization, formula, completing square; (3) Simultaneous equations: substitution, elimination, matrix method. Substitution: Express one variable from one equation, substitute in other. Elimination: Multiply equations to make coefficients equal, add/subtract to eliminate variable. Example: 2x + y = 5 and x - y = 1. Add: 3x = 6 → x = 2, y = 1. Graphical method: Plot both equations, intersection is solution. Shortcut: Choose method based on equation form. Exam tip: Verify solutions in all original equations. For word problems, check reasonableness.