(3x+10)^2=3x+10

9x^2+60x+100=3x+10

9x^2+57x+90=0

3x^2+19x+30=0

D=19^2-4*3*30=361-360=1

x1=(-19-1)/(2*3)=-10/3

x2=(-19+1)/(2*3)=-3

Ответ:

(3х+10)^2=3х+10

9х^2+60х+100=3х+10

9х^2+57х+90=0

Д=57^2-4*9*90=3249-3240=9

х1= (-57+ )/(2*9)=-54/18=-3

х2≈3,3