# How do you factor -100r^2+1?

$- 100 {r}^{2} + 1$
$\textcolor{w h i t e}{\text{XXXX}}$could be written as
${1}^{2} - {\left(10 r\right)}^{2}$
$\textcolor{w h i t e}{\text{XXXX}}$and as such is the difference of squares with factors:
(1+10r)(1-10r)