Question

(a^2+b^2)(c^2+d^2) as the sum of squares​

Answer 1

=(a^2+2ab+b^2)(c^2+2cd+d^2)

=a^2c^2+2a^2cd+a^2d^2+2abc^2+4abcd.

+2abc^2+b^2c^2+2b^2cd+b^2d^2