\[{x}^{2}-10x-{y}^{2}+25\]

1
Rewrite it in the form a22ab+b2{a}^{2}-2ab+{b}^{2}, where a=xa=x and b=5b=5.
x22(x)(5)+52y2{x}^{2}-2(x)(5)+{5}^{2}-{y}^{2}

2
Use Square of Difference: (ab)2=a22ab+b2{(a-b)}^{2}={a}^{2}-2ab+{b}^{2}.
(x5)2y2{(x-5)}^{2}-{y}^{2}

3
Use Difference of Squares: a2b2=(a+b)(ab){a}^{2}-{b}^{2}=(a+b)(a-b).
(x5+y)(x5y)(x-5+y)(x-5-y)

Done

How can we make this solution more helpful?