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A4. Real numbers
Surds

Vocabulary Any number which is written using a square root symbol is called a surd. Numbers such as Ö2 or Ö3 are surds. These are all surds: Ö77, 3+Ö2, 101-Ö61, 5/Ö3... Some surds can be simplified a little: Ö12=Ö(3 x 4)=Ö3 x 2=2Ö3 Ö96=Ö(6 x 16)=Ö6 x Ö16=4Ö6 Some numbers can be simplified further so that they no longer have a square root. In this case they are not called surds: Ö4=2 2Ö25=2 x 5=10 You can do arithmetic with surds: Ö77 x Ö77=77, Ö3 + Ö3=2Ö3, 5Ö7 - 2Ö7=3Ö7 Click on the =? to see how surds can be simplified.

Summary When simplifying surds, look for factors that are square numbers themselves. This page uses WebEQ. To speed up downloading you can install this WebEQ Math Viewer . Click on the Math Viewer icon and you will be taken to the download site.

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