The reduced form of $36 x^{2}-81 y^{2}$ is
i$(6 x+9 y)(6 x-9 y) $
ii$(6 x+9 y)(4 x-5) $
iii.$(9 x+6 y)(9 x-6 y)$
iv. $(9 y-6 x)(9 y+6 x) $
To do: Find the reduced for of $36 x^{2}-81 y^{2}$
Solution:
$36x^{2} - 81y{2}$
= $(6x)^{2} - (9y)^{2}$
Using Identity
$x^{2} - y^{2} = (x + y)(x - y)$
$36x^{2} - 81y^{2}$
= $(6x)^{2} - (9y)^{2} = (6x + 9y) (6x - 9y)$
So option (i) (6x + 9y) (6x - 9y) is CORRECT
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