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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, ie.49=±7. Also: 121=±11,144=±12, 169=±13 196=±14, 225=±15, and so on. Practise your square roots. Press the button to get started. are: and