A2 - a8 = 60
-6a = 60
a = - 10
a3 + a7 = - 40
10a = - 40
a = - 4
50.000-1397.3=-1347.3
20.4+33.603=54.003
-1347.3:54.003=-24.948614
1/2≤cos(2x-π/3)≤1
-π/3+2πk≤2x-π/3≤π/3+2πk
2πk≤2x≤2π/3+2πk
πk≤x≤π/3+πk
Уравнение имеет один корень если дискриминант равен 0
a)tx²-5x+3=0
D=25-12t=0
12t=25
t=2 1/12
b)-3x²-2x+t=0
D=4+12t=0
12t=-4
t=-1/3
c)x²-(2t-1)x+t²+t-2=0
D=(2t-1)²-4(t²+t-2)=0
4t²-4t+1-4t²-4t+8=0
-8t=-9
t=1 1/8