11 Some Useful Shortcuts
Have you noticed that when two factors have the same terms but with the sign between them different, the product is the difference between the terms, each squared? For example, you can multiply the two terms (a + b)(ab) to yield a2b2. You can also factorize a2b2 into (a+b)(ab). This is a shortcut that you can use in working out some algebra problems. Let’s look at a few more.
SUM AND DIFFERENCE IN GEOMETRY
The sum and difference principle can be seen in geometry as well as in algebra. If you take the smaller square from the bigger square in Fig. 11-1, you are left with the shaded area. This is like taking b2 from a2. If you cut the upright piece off and lay it end-on to the other piece, the resulting rectangle ...

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