Add and subtract rational expressions with the same denominator

The  exercise appears under the Algebra II Math Mission. This exercise practices easing into the realm of rational-expression-addition-and-subtraction by first working with expressions that have the same denominator.

Types of Problems
There are two types of problem in this exercise:


 * 1) Find the student that is correct: This problem has an operation with two rational expressions. Users are asked to analyze the answers that the two students got and determine which student is correct. Both or neither of the students may be correct. Add and subtract rational expressions with the same denominator.PNG
 * 2) Add/subtract the rational expressions: This problem has two rational expressions. Users are asked to add or subtract the expressions and type the answers in the text box.

Strategies
As with most work with rational expressions, knowledge and comfort with fractions are important to ensuring success on this exercise.
 * 1) Students can subtract two rational expressions whose denominators are equal by subtracting the numerators and keeping the denominator the same.
 * 2) When the denominators are not the same, users must manipulate them so that they become the same. In other words, they must find a common denominator.
 * 3) If the two denominators do not share any common factors, the common denominator is simply the product of these two denominators.

Real-life Applications

 * 1) Rational expressions and equations appear often in work rate word problems.
 * 2) Rational expressions and equations also can occur in distance=rate*time ($$d=r\times t$$) problem