Question

Factorise m4 - 18m2n2 + 81n4

Answer 1

m4-18m2n2 +81n2
=(m2-n2) whole square

Answer 2

$= > {m}^{4} - 18 {m}^{2} {n}^{2} + 81 {n}^{4}$

$= > {m}^{4} - 9 {m}^{2} {n}^{2} - 9 {m}^{2} {n}^{2} + 81 {n}^{4}$

$= > {m}^{2} ( {m}^{2} - 9 {n}^{2}) - 9 {n}^{2} ( {m}^{2} - 9 {n}^{2} )$

$= > ( {m}^{2} - 9 {n}^{2})( {m}^{2} - 9 {n}^{2} )$

$= > ( {m}^{2} - 9 {n}^{2})^{2}$
As in this question At first we split the middle term and then do calculations.


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