Express (1+x^2)(1+y^2) as the sum of two squares?

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#(1+x^2)(1+y^2)#

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Answer 1 · 2018-01-01T13:04:52

See below.

Mind of

#(a+b)^2-(a-b)^2 = 4a b# or

#a b = ((a+b)/2)^2-((a-b)/2)^2#

Making #a = x^2+1# and #b = y^2+1# we get the solution.