A=2 b=3 c=1
Д=b<span>^2-4ac=9-8=1>0
x1,2= -b+-</span><span>√Д / 2a
x1=1
x2=0.5
Ответ: 1;0.5</span>
<span>y²-x²-6x-9</span>=y²-(x²+6x+9)=y²-(x+3)²=(y- (x+3))(y+(x+3))=(y-x-3)(y+x+3)
<span>х^2 -18х + 84 </span><span>= х</span>² - 2*9*х +81 +3 = (х - 9)² + 3 > 0!