Если х=-½,то (х+3)•2-6х=(-½+3)•2-6•(-½)= -2½+6+6½=-2½+12½=10½=21/2=10,5
вроде так
А)
<span>х² + х = 0
х * (х + 1) = 0
х</span>₁ = 0
х + 1 = 0
х₂ = -1
<span>б)
х² - 4х + 3 = 0
D = 4</span>² - 4 * 1 * 3 = 4 > 0
x₁ = (4 - √4) : (2 * 1) = 1
x₂ = (4 + √4) : (2 * 1) = 3
<span>
в)
5х² + 14х - 3 = 0
</span>D = 14² + 4 * 5 * 3 = 196 + 60 = 256 > 0
x₁ = (-14 - √256) : (2 * 5) = -30 : 10 = -3
x₂ = (-14 + √256) : (2 * 5) = 2 : 10 = 2/10 = 0,2
А) mx=15, x∈Z
x=15/m
m={1;-1;3;-3;5;-5;15;-15}
б) (m-1)*x=18, x∈N
x=18/(m-1)
m-1∈{2;3;6;9;18}
m∈{2+1;3+1;6+1;9+1;18+1}
<span> m∈{3;4;7;10;19}</span>
![f(\frac{1}{x})=(\frac{1}{x})^{-5}=(x^{-1})^{-5}=x^{5}\\\\f(\frac{1}{x})<9x^{8}*f(x)\\\\x^{5}<9x^{8}*x^{-5}\\\\x^{5}<9x^{3} \\\\x^{5}-9x^{3}<0\\\\x^{3}(x^{2}-9)<0\\\\x^{3}(x-3)(x+3)<0](https://tex.z-dn.net/?f=f%28%5Cfrac%7B1%7D%7Bx%7D%29%3D%28%5Cfrac%7B1%7D%7Bx%7D%29%5E%7B-5%7D%3D%28x%5E%7B-1%7D%29%5E%7B-5%7D%3Dx%5E%7B5%7D%5C%5C%5C%5Cf%28%5Cfrac%7B1%7D%7Bx%7D%29%3C9x%5E%7B8%7D%2Af%28x%29%5C%5C%5C%5Cx%5E%7B5%7D%3C9x%5E%7B8%7D%2Ax%5E%7B-5%7D%5C%5C%5C%5Cx%5E%7B5%7D%3C9x%5E%7B3%7D+%5C%5C%5C%5Cx%5E%7B5%7D-9x%5E%7B3%7D%3C0%5C%5C%5C%5Cx%5E%7B3%7D%28x%5E%7B2%7D-9%29%3C0%5C%5C%5C%5Cx%5E%7B3%7D%28x-3%29%28x%2B3%29%3C0)
- + - +
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- 3 0 3
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x ∈ (- ∞ ; - 3) ∪ (0 ; 3)