7) \( -g h^{5} \) 8) 7 9) \( 8 m^{3} n^{6} \) 10) \( -5 x^{3} y z \) 11) \( -k^{2} \) 12) cd

Did you know that mathematical expressions like those you've listed are can be traced back to ancient civilizations? The use of variables and algebraic symbols developed over centuries, with notable contributions from Arabic, Greek, and Indian mathematicians. Algebra started gaining its modern structure in the Middle Ages and has since become an essential tool in solving real-world problems and advanced scientific equations. In real life, expressions like \( -g h^{5} \) or \( 8 m^{3} n^{6} \) can represent various quantities, like forces in physics or volumes in geometry. Engineers use similar formulas to calculate loads, while economists apply them to express supply and demand equations. Whether you're building a bridge or analyzing financial trends, these expressions help in modeling complex scenarios in a manageable way!