\(a,5x^2-10x=5x.\left(x-2\right)\)

\(b,x^3y-xy=xy.\left(x^2-1\right)=xy.\left(x-1\right).\left(x+1\right)\)

\(c,x^2-5x+xy-5y=x.\left(x-5\right)+y.\left(x-5\right)=\left(x-5\right).\left(x+y\right)\)

\(d,x^2-1+4.\left(x+1\right)=\left(x-1\right).\left(x+1\right)+4.\left(x+1\right)=\left(x+1\right).\left(x-1+4\right)=\left(x+1\right).\left(x+3\right)\)

\(e,x^2-y^2+xz+yz=\left(x-y\right).\left(x+y\right)+z.\left(x+y\right)=\left(x+y\right).\left(x-y+z\right)\)

\(f,x^2-6x+9-y^2=\left(x-3\right)^2-y^2=\left(x-3-y\right).\left(x-3+y\right)\)

\(\left(x^2-2x-y^2+1\right)=\left(x^2-2x+1\right)-y^2=\left(x-1\right)^2-y^2=\left(x-1-y\right).\left(x-1+y\right)=\left(x-y-1\right).\left(x+y-1\right)\)

\(\left(x-y-1\right).\left(x-1+y\right):\left(x-y-1\right)=x-1+y\)

\(\Rightarrow\left(x^2-2x-y^2+1\right):\left(x-y-1\right)=x-1+y\)

\(x\times15,6-5,6\times x=7,75:5\)

\(x\times\left(15,6-5,6\right)=1,55\)

\(x\times10=1,55\)

\(x=1,55:10\)

\(x=0,155\)

không có gì