i'm having troubles with some sums

how would you factorize completely

9a(squared) - b(squared)?

or an expression like

27x(squared) - 1/3y(squared)

its difficult. have many more.

4 answers

9a^2 - b^2
= (3a)^2- (b)^2
= (3a+b)(3a-b)

i couldn't understand the second one though. Hope it helps!!! :-)
whenever you have the difference of two squares
the factors are the sum and the difference of the two that are squared.
a^2-b^2 ( a + b )( a - b )
27x(squared) - 1/3y(squared)
first take (1/3) out

(1/3) (3^4 x^2 - y^2)

(1/3)(3^2 + y)(3^2 - y)

(1/3)(9+y)(9-y)
1/3) (3^4 x^2 - y^2)

(1/3)(3^2 x + y)(3^2 - y)

(1/3)(9x+y)(9x-y)