What is the factored from of the expression k2-9h2?

k^(2) - 9h^(2)

First recognise that '9' = 3^(2)

Hence

k^(2) - 3^(2)h^(2) =>

k^(2) - (3h)^(2)

(Factor

(k - 3h)( k + 3h) Fully factored.

NB

First if any coefficients are squared numbers.

Secondly, two squared terms with a negative(-) between them factors. This does NOT happen if there is a positive(+) between.

Lastly the bracketed terms should each have a different sign.

NNB The Pythagorean Eq'n ; h^(2) = a^(2) + b^(2) does NOT factor.

However, if algebraically rearranged to

; a^(2) = h^(2) - b^(2) factors to a^(2) = (h - b)(h + b)