А) 7/9 * 2/5 б) 12/13 * 26/27 в) 3 3/5 * 2 1/12 г) 4 2/7 * 2 4/5 д) 2 5/8 * 4/21 е) 6/7 *2 13/18
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Ответы на вопрос:
7/9*2/5=14/45 12/13*26/27=8/7 3 3/5*2 1/12=18/5*25/12=15/2 4 2/7* 2 4/5= 16/7*14/5=32 2 5/8*4/21=21/8*4/21=1/2 6/7*2 13/18=6/7* 36/18=38/21
log²(2) x + log(2) y - 2log²(2) x = 0
9x²y - xy² = 64
x,y > 0
разложим первое
log(2) x = a
log(2) y = b
a² + b - 2b² = (a - b)(a + 2b)
d=b² + 8b² = 9b²
a12= (-b+-3b)/2 = b -2b
(log(2) x - log(2) y)(log(2)x + 2log(2) y) = 0
произведение = 0, значит один из множителей = 0
1. log(2) x - log(2) y = 0
log(2) x = log(2) y
x = y подставляем во 2
9x²x - xx² = 64
8x³ = 64
x³ = 8
x = 2
y = 2
2. log(2)x + 2log(2) y = 0
log(2)x + log(2) y² = 0
log(2) xy² = 0
xy² = 1
x = 1/y²
9x²y - xy² = 64
9(1/y²)² y - 1/y² * y² = 64
9y³ - 1 = 64
y³ = 65/9
y = ∛(65/9)
x = 1/∛(65/9)² = ∛(81/4225)
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