How can a^2 - 36b^2 be factorized?The expression given is a squared - 36 b squared

Remember that a^2 - 36b^2 is the same as a^2 + 0ab -
36b^2.

Then factor like any such
polynomial:

(a + __) (a - __)   -- a being the square root
of a^2. Also, the negative sign before the third term tells you the signs are different
(+ and -).

(a + 6b) (a - 6b) -- 6b being the square root of
36b^2. Since 6ab and -6ab cancel each other out, there is no need to figure out which
one is positive and which negative.