А)x²/(x²-9)=(12-x)/(x²-9)⇒
x²=12-x;⇒x²+x-12=0
x₁,₂=-1/2⁺₋√1/4+12=-1/2⁺₋7/2;
x₁=-1/2+7/2=-6/2=-3;
x₂=-1/2-7/2=-8/2=-4;
б)6/(x-2)+5/x=3⇒(6x+5(x-2))=3x(x-2)⇒6x+5x-10=3x²-6x;⇒
3x²-17x+10=0;
x₁,₂=(17⁺₋√(17²-4·3·10))/6=(17⁺₋13)/6;
x₁=(17+13)/6=30/6=5;
x₂=(17-13)/6=4/6=2/3;
A)3x-12+2x+6=8
5x=14
x=14/5
b)x^2+2x-3=x^2-2x
4x=3
x=3/4
Вроде так.................