<span>y=-0,5x^2+2,5 и y=2x^2+x
0.5x</span>²+2.5=2x²+x
1.5x²+x-2.5=0 3x²+2x-5=0 √D=√4+60=8
x1=1/6[-2-8] = -10/6=-5/3 x2=1/6[-2+8] =1
(2x - 7)(2x + 7) ≥ 6x - 51
4x² - 49 - 6x + 51 ≥ 0
4x² - 6x + 2 ≥ 0
2x² - 3x + 1 ≥ 0
2x² - 3x + 1 = 0
D = (-3)² - 4 * 2 * 1 = 9 - 8 = 1
2x² - 3x + 1 = 2(x - 1)(x - 0,5)
(x - 1)(x - 0,5) ≥ 0
+ - +
_________[0,5]________[1]__________
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Ответ : x ∈ (- ∞ ; 0,5] ∪ [1 ; + ∞)
Все координаты должны быть в k раз больше
b = (4k; -3k)
a * b = k * (4; -3) * (4; -3) = k (16 + 9) = 25k = 75
k = 3
b = (12; -9)