(19-y)=7/1/3
19-y=21
y=19-21
y=-2
№1
1.0,4с=0
с = 0
2.0,4с=1
с = 2,5
3.0,4с=-1
с=-2,5
4.0,4с=10
с=25
№2
1.6bс = 12
bс = 2
b = 1 c = 2
b = 0.5 c = 42.6bc = -60bc = -10b = -1 c = 10b = -2 c =5
3.6bc = 0
bc = 0
b = 1 c = 0
b =0 c =37
4.6bc = 3
bc = 0.5
b = 1 c = 0.5
b = 2 c = 0.25
(a-b)x-(a-b)y=(a-b)(x-y)
ответ 2.
3+9=12 39+36=75 ∉
4+8=12 48+36=84 ∈
5+7=12 57+36=93 ∉
Ответ: 48.
4.
x²-4>0
(x-2)(x+2)>0
x∈(-∞; -2)∨(2; +∞)
3. sin(α-3π/2)*cos(2π-α)*sin(π+α)=sin(-(3π/2-α))*cosα*(-sinα)=-(-cosα)*cosα*(-sinα)=-cos²α*sinα