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A fractional expression (for our purposes) is any fraction where there is at least one additional operation in the top or bottom. For example, consider this question: 
Both the top and bottom have an additional operation hidden in them ... in this case, adding. It's perfectly clear what has to be done ... you simplify the top, simplify the bottom, and then divide: 
Now consider what your calculator sees when you enter the question above. You can't make it look like a fraction ... all you can do is show the 'divide':  Your calculator has no idea that this was really a fraction! So what does it do? It applies the order of operations rule that says 'do dividing before adding', and divides the 6 by 2:  ... which of course is the wrong answer! Your calculator will always get the wrong answer to questions like this ... unless you know how to tell it that the question is really a fraction. Here's how you do it. Whenever there is an additional operation in the top or bottom of a fraction (in this case, addition in both), surround the top and/or bottom in brackets.  The brackets tell the calculator to do those parts first. The calculator will now do the question correctly. 
Additional operations on the top or bottom of a fraction can include addition, subtraction, multiplication, or division, or any combination of those. |