Х =2\х+1 х=[2+1]\x x^2=2+x x^2 -х -2 =0
D= 1+4^1^2 =9
sqrt d =з
х1=(1+3)/2=2
x2=(1-3)/2=_1
1
3x²+3x-16x+14=0
3x²-13x+14=0
D=169-168=1
x1=(13-1)/6=2
x2=(13+1)/6=7/6
2
ОДЗ
x∈(-∞;0]
x1=0
x²+6x+72=0
D=36-288=-252<0⇒x-любое
x²+4x-5=0
x2+x3=-4 U x2*x3=-5
x2=-5
x3=1не удов усл