b)
3-3cosx=2(< var > 2cos^{2}(x) < /var ><var>2cos
2
(x)</var> -1)
4< var > cos^{2}(x)+3*cos(x)-5=0 < /var ><var>cos
2
(x)+3∗cos(x)−5=0</var> cos(x)=t,-1<t<1
4t^2+3t-5=0
D=9+80=89
< var > \sqrt{D}=89\approx=9.4 < /var ><var>
D
=89≈=9.4</var>
< var > x_1=(-3-9.4)/8=-5/8 < /var ><var>x
1
=(−3−9.4)/8=−5/8</var>
< var > x_2=(-3+9,4)/8=0.8 < /var ><var>x
2
=(−3+9,4)/8=0.8</var>
Обратная замена
cosx=-5/8 cosx=0.8
x=+-arccos(-5/8)+2< var > \pi < /var ><var>π</var> *n x=+-arccos(0.8)+2< var > \pi < /var ><var>π</var> *n
Пошаговое объяснение:
7x = -30 + 2x
7x - 2x = 30
5x = 30
x = 30:5
x = 6
16 - 18x = -25x - 12
25x - 18x = -12 - 16
7x = -28
x = -28 : 7
x = -4
-17x + 20 = 7x - 28
7x + 17x = 20 + 28
24x = 48
x = 48:24
x = 2
20 - 2x = 27 + x
x + 2x = 20 - 27
3x = -7
x = -7 : 3
x = -2 1/3
0,2x + 4,3 = 0,4x - 6,5
0,4x - 0,2x = 4,3 + 6,5
0,2x = 10,8
x = 10,8 : 0,2
x = 54
0,6x + 100 = 0,9x + 1
0,9x - 0,6x = 100 - 1
0,3x = 99
x = 99:0,3
x = 330
-9/14 x + 18 = -2/3 x + 17
-9/14 x + 2/3 x = 17 - 18
-27/42 x + 28/42 x = -1
1/42 x = -1
x = -1 * 42/1
x = -42
-8/15 x - 11 = 4/9 x + 11
-8/15 x - 4/9 x = 11 + 11
-24/45 x - 20/45 x = 22
-44/45 x = 22
x = 22 * (-45/44)
x = -45/2
x = -22 1/2
Пошаговое объяснение:
Округляем n до целого числа n=8
проверяем