Ответ:
(√5+1)^2+(√5-1)^2= 5+2 корень из 5 + 1 +5 + 1 - 2 корень из 5= 12
1) 6X^2 - 294 = 0
6X^2 = 294
X^2 = 49
X1 = + 7
X2 = ( - 7 )
...............................................
2) 7X^2 - 2X + 3 = 0
D = 4 - 4*7*3 = 4 - 84 = ( - 80 )
D < 0
Корней нет
(2x+1)^2-(5+x)*(x-5)=
=4x^2+4x+1-(-25+x^2)=
=4x^2+4x+1+25-x^2=
=3x^2+4x+26