Learn math, science, English SAT & ACT from
highquaility study
videos by expert teachers
Thank you for watching the preview.
To unlock all 5,300 videos, start your free trial.
Adding and Subtracting Rational Expressions  Problem 1
Carl Horowitz
Carl Horowitz
University of Michigan
Runs his own tutoring company
Carl taught upperlevel math in several schools and currently runs his own tutoring company. He bets that no one can beat his love for intensive outdoor activities!
Whenever we are adding or subtracting fractions we always need a common denominator and in order to do that when dealing with rational expressions I always find it easiest to factor out the denominators completely.
So looking at my first denominator I see I have a common factor 7, so I can take that out 7 leaving me with 1 plus 2x. Looking at my second denominator, I see that I have a 5 I can take out leaving me with 1 plus 2x as well.
So finding my LCD, my least common denominator, I know I need a 1 plus 2x and I also need a number that has a 7 and a 5. The only number that has both of those terms the smallest one is 7 times 5 35. So in order to obtain a 35 I need to multiply this first one by 5 over 5 and the second term by 7 over 7. So what I end up with then is 20 over 35(1 plus 2x) plus 14 over 35(1 plus 2x). Once our denominators are the same, we can just combine like terms in the numerator giving us 34 over 35(1 plus 2x).
In this case nothing can cancel sometimes we will be able to factor, cancel some things, in this case what we are left with is our final answer.
Please enter your name.
Are you sure you want to delete this comment?
Carl Horowitz
B.S. in Mathematics University of Michigan
He knows how to make difficult math concepts easy for everyone to understand. He speaks at a steady pace and his stepbystep explanations are easy to follow.
Sample Problems (9)
Need help with a problem?
Watch expert teachers solve similar problems.

Adding and Subtracting Rational Expressions
Problem 1 6,512 viewsSimplify:
4 + 2 7 + 14x 5 + 10x 
Adding and Subtracting Rational Expressions
Problem 2 5,475 viewsSimplify:
2 − x − 3 x − 2 x² + 2x + 4 x³ − 8 
Adding and Subtracting Rational Expressions
Problem 3 5,002 viewsSimplify:
4b − 3b b² + 6b + 5 b² + 5b + 4 
Adding and Subtracting Rational Expressions
Problem 4 1,198 views 
Adding and Subtracting Rational Expressions
Problem 5 1,148 views 
Adding and Subtracting Rational Expressions
Problem 6 1,212 views 
Adding and Subtracting Rational Expressions
Problem 7 1,205 views 
Adding and Subtracting Rational Expressions
Problem 8 1,073 views 
Adding and Subtracting Rational Expressions
Problem 9 1,175 views
Comments (0)
Please Sign in or Sign up to add your comment.
·
Delete