Expert: Lynn Houston - 11/12/2008

Question
I am just not getting it :(
Simplify the following expressions by combining as many terms as possible: 3xy + 5xy; 9x^2t - 7x^2t; 2xy + 6y + 8xy; 4 sqrt x + 3 sqrt xy + 7 sqrt xy - sqrt x;

Answer
combining terms, just means, take all the terms that are the same and add them together.

Let's say you had 5x + 2x, but let's give x a value (x=2).  Your equation would be 5(2) + 2(2) = 14, but it's also (5+2)(2)=14.  Since the 2 is the same for both, you just add the 5 & 2 (it's also the reverse of the distributive property).  So the answer to your questions are:

3xy + 5xy = 8xy
9x^2t - 7x^2t = 2x^2t
2xy + 6y + 8xy = 10xy + 6y
4 sqrt x + 3 sqrt xy + 7 sqrt xy - sqrt x = 3 sq rt x + 10 sq rt xy