35 168. Literal Simultaneous Equations. In solving literal simultaneous equations, the method of elimination by addition or subtraction is usually the best. 169. Certain equations in which the unknown quantities occur in the denominators of fractions may be readily solved without previously clearing of fractions. XV. SIMULTANEOUS EQUATIONS. CONTAINING MORE THAN TWO UNKNOWN 170. If we have three independent simple equations, containing three unknown quantities, we may combine any two of them by one of the methods of elimination explained in §§ 164 to 166, so as to obtain a single equation containing only two unknown quantities. We may then combine the remaining equation with either of the other two, and obtain another equation containing the same two unknown quantities. By solving the two equations containing two unknown. quantities, we may obtain their values; and substituting them in either of the given equations, the value of the remaining unknown quantity may be found. We proceed in a similar manner when the number of equations and of unknown quantities is greater than three. The method of elimination by addition or subtraction is usually the most convenient. |