Сумма смежных углов равна 180 градусов.
угол СОД = х (СОД и ДОС - это один угол)
угол ДОК = 3.5 х ( в 3.5 раза больше)
х+3.5х=180
4.5х=180
х=40 Угол ДОС =40
1.149. ((x+3)/(x²-3x)+(x-3)/(x²+3x))·(9x-x³)/(x²+9)=
=((x+3)/x(x-3)+(x-3)/x(x+3))·x(9-x²)/(x²+9)=[((x+3)²+(x-3)²)/x(x²-9)]·x(9-x²)/(x²+9)=
=(x²+6x+9+x²-6x+9)·x·(9-x²)/(x(x²-9)·(x²+9)=(2·(x²+9)·x(9-x²))/(x·(x²-9)·(x²+9))=-2;
1.150 [(x+3)/(x-3)-(x-3)/(x+3)]:2x/(9-x²)=((x+3)²-(x-3)²)/(x²-9):2x/(9-x²)=
=(x²+6x+9-x²+6x-9)·(9-x²)/(2x·(x²-9))=(12x(9-x²)/2x(x²-9)=-6;
1.151 2a/(a+1)+(3/(a-1)²-3/(a²-1)):3/(a²-2a+1)=
=2a/(a+1)+[(3·(a+1)-3(a-1))/(a-1)²(a+1)]:3/(a-1)²=
=2a/(a+1)+(3a+3-3a+3)·(a-1)²/[3(a-1)²·(a+1)]=2a/(a+1)+6/3(a+1)=(2a+2)/(a+1)=2;
(5a+7-2b)(5a+7+2b)
(2√27+√3)^2=(6√3+√3)^2=(7√3)^2=147
19-8√3=(4-√3)^2
1) Формула вершины параболы:
х₀ = - b / 2a
y₀ = y (x₀)
x₀ = - (- 2) / - 2 = - 2
y₀ = - (- 2)² - 2 * (- 2) + 5 = - 4 + 4 + 5 = 5
Координаты вершины параболы: (- 2; 5)
2) у (4) = - 4² + 2 * 4 - 6 = - 16 + 8 - 6 = - 14
Ответ: - 14
<span>а) 3x - 5 - 2x + 7 = (3x - 2x) + (-5 + 7) = x + 2
б) 2a - y - 3a + 2y = (2a - 3a) + (2y - y) = -a + y
в) 4(a - x) - 2(3a - x) = 4a - 4x - 6a - 2x = (4a - 6a) + (-4x - 2x) = -2a - 6x
г) - (3a - c) + 3(3c - a) = -3a + c + 9c - 3a = (-3a - 3a) + (c + 9c) = -6a + 10c
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</span><span>а) b + (-7m + 2n) = b - 7m + 2n
б) -3p - (-5x + 2y) = -3p + 5x - 2y
в) -(a - 4b) + (-8x + 3y) = -a + 4b - 8x + 3y
г) (a - 9) - (13 - a) + (11 - a) = a - 9 - 13 +a + 11 - a = (a - a + a) + (11 - 9 - 13) = a - 11</span>