<span>(x-2)*(x+2)+x^2 +х^2 -1=x^2-4+x^2+x^2-1=3x^2-3=3(x^2-1)=3(x-1)(x+1)</span>
-8x+9=-7
-8x=-7-9
-8x=-16
x=2
методом интервалов:
---------+++++++---------+++++++
-7 0 1/12
X=2-y; 2(2-y)^2+(2-y)y+y^2=16
2*(4-4y+y^2) +2y-y^2+y^2-16=0
8-8y+2y^2+2y-y^2+y^2-16=0
2y^2-6y-8=0; y^2-3y-4=0; D=9-4*(-4)=25=5^2; y1=(3-5)/2=-1; y2=4;
x1=2+1=3;
x2=2-4=-2. Ответ(3;-1) ; (-2;4)