Factor: 100 - h^2.

1. Check that the binomial fits the pattern: 100 is 10 squared, and h squared is h squared, so this is a difference of squares. 2. Write the product of conjugates using a equals 10 and b equals h: (10 - h)(10 + h). 3. Check by multiplying: 100 + 10h - 10h - h squared gives back 100 - h squared. 4. Rewriting the original as h squared - 100 first and factoring that instead gives (h - 10)(h + 10), which is a different expression with the opposite sign. _Source: OpenStax Elementary Algebra (CC BY 4.0), Ch 7 "Factoring", section 7.4 Factor Special Products_