[tex]\bf{-5x^{2} +10x-25 }[/tex]
[tex]\bf{Rewrite \ 10 \ as:5\cdot2.}[/tex]
[tex]\bf{Rewrite \ 25 \ as:5\cdot5.}[/tex]
[tex]\bf{=-5x^2+5\cdot \:2x-5\cdot \:5}[/tex]
[tex]\bf{Factor \ the \ common \ term \ 5.}[/tex]
[tex]\bf{=5(-x^{2} +2x-5) \ \ \to \ \ \ Answer }[/tex]