Factorize the following :
(i)`28 a^2+14 a^2b^2-21 a^4`
(ii) `a^4b-3a^2b^2-6a b^3`
(iii) `2l^2m n-3l m^2n+4l m n^2`
(iv) `x^4y^2-x^2y^4-x^4y^4`

Explanation

GivenL:

`(1) 28 a^2+14 a^2b^2-21 a^4`

`=> 7xx4a^2+7xx2 a^2b^2-7xx3 a^4`

`=> 7a^2(4+2b^2-3 a^2)`

`(2) a^4b-3a^2b^2-6a b^3`

`=> ab(a^3-3ab-6b^2)`

`(3) 2l^2m n-3l m^2n+4l m n^2`

`=> lmn(2l-3m+4n)`

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