Question

expand using identities (x2+y2)(x2-y2)

Answer 1

=x2(x2-y2)+y2(x2-y2)
=x4-x2y2+x2y2-y4
=x4-y4

Answer 2

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By algebraic identity ,

( a + b )( a - b ) = a² - b²

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Here ,

a = x² , b = y² ,

Now ,

( x² + y ² )( x² - y² )

= ( x² )² - ( y² )²

= x⁴ - y⁴

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