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| F | G | H | I | J |
Further info
Tech
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Introduction Further info Tech |
| B1. Indices | |
| Negative square root |    |
| 3 x 3=9, and -3 x -3=9 too. So
both 3 and -3 are square roots of 9. This could also be written as 3²=9 and (-3)²=9. Similarly, 5²=25 and (-5)²=25. Any positive number has both a positive and a negative square root. The two square roots of 49 are 7 and -7 for example. You need to be clear what is expected when you are asked to provide the square root of a number. Sometimes this might mean only the positive value, sometimes it might mean both positive and negative. The same issue arises when the Ö symbol is used. Does Ö49 = 7 only or does Ö49 = ±7? This should be clear from the context of the problem you are working on. Assuming the symbol is asking for both values: Ö121=±11,Ö144=±12, Ö169=±13 Ö196=±14, Ö225=±15, and so on. Practise your square roots. Press the button to get started and try to get 10 correct answers at least before you move on: |