cos2t=1-2*=1-2*=1-1.28=-0.28
20*cos2t=20*(-0.28)=-5.6
Sqrt(x^2 + 4x + 4) - sqrt(x^2 - 6x + 9) = sqrt((x + 2)^2) - sqrt((x - 3)^2) = |x + 2| - |x - 3|
Если х = -7:
|-7 + 2| - |-7 - 3| = |-5| - |-10| = 5 - 10 = -5
Если х = -4:
|-4 + 2| - |-4 - 3| = |-2| - |-7| = 2 - 7 = -5
Ответ: -5
X=1,5y x-y=7 1,5y-y=7, 0,5y=7 y=14,x=21