Given:
[tex](x+5)^2+4(x+5)+12=0[/tex]let u = x+5
so, the equation will become:
[tex]u^2+4u+12=0[/tex]so, the equation is quadratic in form because the substitution u = x+5
The answer is the first statement
Note:
the second statement is wrong, because when the equation expanded, it will be a second degree polynomials not fourth degree
Also, the last 2 statements are wrong, because it is quadratic equation.