Ab+ac-a=a(b+c-1)
--------------------------------
D= b^2-4ac;
D=(-1)^2-4*7*(-8)= 1+224=225
Х1,2= -B+-корень из D/2a
X1= 1+15/14=16/14=8/7
X2= 1-15/14=-14/14= -1.
sinx(2cosx+sqrt(2))=0
sinx=0
x=-П;0 П
сosx=-sqrt(2)/2
x=-5/4П; -3/4П; 3/4П; 5/4П
<span>8<x<12
-3<y<-1
</span><span><span>1<-y<3</span>
</span><em><u>5<x+y<11</u></em>
<em><u>9<x-y<15</u></em>