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# Difficult question GCSE watch

1. show that the sum of 15^12 and 12^16 is a multiple of 9
2. 15^12 +12^16
(3x5)^12 +(3x4)^16

(3)^12 x (5)^12 + (3)^16 x(4)^16

And since 3^2 =9, you should be able to take it from here.
3. 15^12 + 12^16

15^12 + 120000 ^ 12 = 120015 ^12

120,015 / 9 = 13335 = A whole number.

So therefore it is divisible by 9.

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Updated: February 14, 2018
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