Question

use a suitable identity to get each of the following products
$(a { }^{2} + b {}^{2}) ( - a {}^{2} + b {}^{2} )$
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Answer 1

We can write it as follows:
(b^2+a^2)(b^2-a^2)=b^4-a^4

We have used the identity (m+n)(m-n)=m^2-n^2