Comment Comment by chisquared > Then you've just skipped the case when a^2 - b^2 is negative.Not really. If b > a, then swap them to conclude that b^2 - a^2 = (b + a)(b - a), which is what the visual proof demonstrates.Your conclusion is equivalent to saying that a^2 - b^2 = (a + b)(a - b). parent chisquared 1 year ago
Not really. If b > a, then swap them to conclude that b^2 - a^2 = (b + a)(b - a), which is what the visual proof demonstrates.
Your conclusion is equivalent to saying that a^2 - b^2 = (a + b)(a - b).