2002 IMO Problems/Problem 5

Problem

Find all functions $f:\Bbb{R}\to \Bbb{R}$ such that

$(f(x)+f(z))(f(y)+f(t))=f(xy-zt)+f(xt+yz)$

for all real numbers $x,y,z,t$ .

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2002 IMO (Problems) • Resources
Preceded by Problem 4	1 • 2 • 3 • 4 • 5 • 6	Followed by Problem 6
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