ПОМОГИТЕ ПОЖАЛУЙСТА!!!! СРОЧНО!!!!

$4.1\\\\ (x^2-4x)+x-4=0\\\\ x*(x-4)+1*(x-4)=0\\\\ (x+1)*(x-4)=0\\\\ x+1=0\ \ or\ \ x-4=0\\\\ x=-1\ \ or\ \ x=4$
Ответ: $-1;\ 4$
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$4.2\\\\ x^2+3x-28=0\\\\ x^2+7x-4x-28=0\\\\ x*(x+7)-4*(x+7)=0\\\\ (x-4)*(x+7)=0\\\\ x-4=0\ \ or\ \ x+7=0\\\\ x=4\ \ or\ \ x=-7$

Ответ: $4;\ -7$
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$5.1\\\\ a^2+2a=a^2+2*a*1+1^2-1^2=(a+1)^2-1$
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$5.2\\\\ x^2-12x=x^2-2*x*6+6^2-6^2=(x-6)^2-36$
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$5.3\\\\ a^4+2a^2b^2+9b^4=(a^2)^2+2*a^2*b^2+(b^2)^2+8b^4=\\\\ =(a^2+b^2)^2+8b^4$