Algebra correction
posted by Rae Rae .
The last one which you were asking where the b came from I typed the wrong problem sorry.
the problem is 49a^2b^2
Is the answer: (7+ab)(7ab)

(7ab)(7+ab)
the difference of two squares
(sqrt first + sqrt second)(sqrt first  sqrt second) 
Check these by multiplying them out.

How about answering your own question.
will I get 49a^2b^2 if I simplify (7+ab)(7ab) ??
now try (7 + ab)(7  ab) 
Thank you now I understand how to check them to see if there right. Thanks Damon, and thanks Reiny.