A system of two equations can be classified as follows:
If the slopes are the same but the y-intercepts are different, the system has no solution.
If the slopes are different, the system has one solution.
If the slopes are the same and the y-intercepts are the same, the system has infinitely many solutions.
Definition Linear Equation in One Variable A linear equation in one variable is an equation that can be written in the form ax+b=c, where a, b, and c are real numbers and . Linear equations are also first-degree equations because the exponent on the variable is understood to be 1. Objective 3: Identify Equations That Are Contradictions and Those That Are Identities A conditional equation is an equation that is true for some values of the variable but not for others. Every linear equation that is a conditional equation has one solution. However, not every linear equation in one variable has a single solution. There are two other cases: no solution and the solution set of all real numbers. Consider the equation x x 1. No matter what value is substituted for x, the resulting value on the right side will always be one greater than the value on the left side. Therefore, the equation can never be true. We call such an equation a contradiction. It has no solution. Its solution set is the empty or null set, denoted by { } or , respectively. Now consider the equation xx2x. The expression on the left side of the equation simplifies to the expression on the right side. No matter what value we substitute for x, the resulting values on both the left and right sides will always be the same. Therefore, the equation is always true. We call such an equation an identity. It
