![8^7 - 2^{15} = (2^3)^7 - 2^{15} = 2^{21} - 2^{15} =](https://tex.z-dn.net/?f=8%5E7+-+2%5E%7B15%7D+%3D+%282%5E3%29%5E7+-+2%5E%7B15%7D+%3D+2%5E%7B21%7D+-+2%5E%7B15%7D+%3D+)
![= 2^{15}(2^6 - 1) = 2^{15}(64-1) = 2^{15}\cdot63](https://tex.z-dn.net/?f=+%3D+2%5E%7B15%7D%282%5E6+-+1%29+%3D+2%5E%7B15%7D%2864-1%29+%3D+2%5E%7B15%7D%5Ccdot63+)
А 63 делится на 7. Значит 8^7 - 2^15 тоже делится на 7.
5y-4x=11
-4x-5y=-19
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5y -4x = 11
-5y -4x = -19
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-8x = -8
x = 1
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5y - 4*1 = 11
5y - 4 = 11
5y = 15
y = 3
Ответ: (1; 3)
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x + 7y = 64
x - 7y = -62
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2x = 2
x = 1
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1 + 7y = 64
7y = 63
y = 9
Ответ: (1;9)
Как то так...............