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(7х²-4х+8)-(4х²-х-5)=7х²+4х+8-4х²-х+5=3х<span>²-3х+13.
ответ: 3х</span><span>²-3х+13</span>
{xy=12, {(y+1)y=12
{x=y+1, {x=y+1
y^2+y=12
y^2+y-12=0
D=1+48=49 Корень из D =7
y1= (-1+7)/2=3
y2=(-1-7)/2=-4
x1=4
x2=-3 Ответ: (3;4) (-3;-4)
<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>