0 \\
y_{1} =-3 \\
y _{2} =-4 \\
x^{2}+4x+3=0 \\
D>0 \\
x_{1} =-1 \\
x_{2} =-3 \\
x^{2} +4x+4=0 \\
D=0 \\
x_{3,4} =-2" alt="( x^{2} +4x) ^{2} +7x ^{2} +28x+12=0 \\
( x^{2} +4x) ^{2} +7( x^{2} +4x)+12=0 \\
x^{2} +4x=y \\
y ^{2} +7y+12=0 \\
D>0 \\
y_{1} =-3 \\
y _{2} =-4 \\
x^{2}+4x+3=0 \\
D>0 \\
x_{1} =-1 \\
x_{2} =-3 \\
x^{2} +4x+4=0 \\
D=0 \\
x_{3,4} =-2" align="absmiddle" class="latex-formula">