\(\Leftrightarrow\left(x^2-6x+9\right)^2-1-15\left(x^2-6x+10\right)=0\)
\(\Leftrightarrow\left(x^2-6x+8\right)\left(x^2-6x+10\right)-15\left(x^2-6x+10\right)=0\)
\(\Leftrightarrow\left(x^2-6x+10\right)\left(x^2-6x-7\right)=0\)
\(\Leftrightarrow\left(x^2-6x+10\right)\left(x^2+x-7x-7\right)=0\)
\(\Leftrightarrow\left(x^2-6x+10\right)\left(x+1\right)\left(x-7\right)=0\)
\(Vi:x^2-6x+10=0\Leftrightarrow\left(x-3\right)^2+1>0,\forall x\)
\(\Leftrightarrow x+1=0\Leftrightarrow x=-1\)
\(hay:x-7=0\Leftrightarrow x=7\)
\(V...\)
\(:)\)