стрелочка вверх- ответ по первому
по второму, ответ: 19/4
<span>x-2y=6 |*2
2x-4y=12
</span>-2x-y=11 - сложим
__________
-5y=23
y = -4.6
x = 6 +2y = 6 + 2 * (-4.6) = -3.2
<span>Найдем 3x-11y = 3*(-3,2) - 11*(-4,6) = 41</span>
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√4*√7- 2√2a 2√7-2√2a 2(√7-√2a) =____________=_______________= __________________=
5((√2a)²-(√7)²) 5(√2a-√7)(√2a+√7) <span> 5(√2a+√7) ( √2a-√7)</span>
<span> 2</span>
<span>=_________</span>
<span>-5(√2a+√7
</span>